Cambridge IGCSE · thinka-original Practice Paper

2026 Cambridge IGCSE Mathematics (0580) Practice Paper with Answers

Thinka Jun 2026 (V3) Cambridge IGCSE-Style Mock — Mathematics (0580)

200 marks240 mins2026
An original Thinka practice paper modelled on the structure and difficulty of the Jun 2026 (V3) Cambridge IGCSE Mathematics (0580) paper. Not affiliated with or reproduced from Cambridge.

Paper 2 (Extended Non-Calculator)

Answer all questions. Calculators must not be used in this paper. Show all necessary working clearly.
28 Question · 104 marks
Question 1 · short-answer
2 marks
Work out \(\sqrt{48} - 2\sqrt{27} + \sqrt{75}\).

Give your answer in the form \(a\sqrt{3}\), where \(a\) is an integer.
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Worked solution

Simplify each surd into multiples of \(\sqrt{3}\):
\(\sqrt{48} = \sqrt{16 \times 3} = 4\sqrt{3}\)
\(2\sqrt{27} = 2\sqrt{9 \times 3} = 2 \times 3\sqrt{3} = 6\sqrt{3}\)
\(\sqrt{75} = \sqrt{25 \times 3} = 5\sqrt{3}\)

Combine the terms:
\(4\sqrt{3} - 6\sqrt{3} + 5\sqrt{3} = (4 - 6 + 5)\sqrt{3} = 3\sqrt{3}\)

Marking scheme

M1 for at least two of \(4\sqrt{3}\), \(6\sqrt{3}\), \(5\sqrt{3}\) seen (or simplifying \(\sqrt{48}=4\sqrt{3}\), \(\sqrt{27}=3\sqrt{3}\), \(\sqrt{75}=5\sqrt{3}\))
A1 for \(3\sqrt{3}\)
Question 2 · short-answer
3 marks
A sector of a circle has radius \(9\text{ cm}\) and sector angle \(80^\circ\).

Calculate the perimeter of the sector.
Give your answer in the form \(a + b\pi\), where \(a\) and \(b\) are integers.
Show answer & marking scheme

Worked solution

1. Find the arc length:
\(\text{Arc length} = \frac{80}{360} \times 2 \times \pi \times 9 = \frac{2}{9} \times 18\pi = 4\pi\text{ cm}\)

2. Find the total perimeter by adding the two radii:
\(\text{Perimeter} = \text{arc length} + 2r = 4\pi + 2(9) = 18 + 4\pi\text{ cm}\)

Marking scheme

M1 for \(\frac{80}{360} \times 2 \times \pi \times 9\) oe
A1 for arc length \(= 4\pi\)
A1 for \(18 + 4\pi\) or \(4\pi + 18\)
Question 3 · short-answer
2 marks
Work out \(1\frac{5}{7} \div 2\frac{2}{5}\).

Give your answer as a fraction in its simplest form.
Show answer & marking scheme

Worked solution

Convert both mixed numbers to improper fractions:
\(1\frac{5}{7} = \frac{12}{7}\)
\(2\frac{2}{5} = \frac{12}{5}\)

Divide by multiplying by the reciprocal:
\(\frac{12}{7} \div \frac{12}{5} = \frac{12}{7} \times \frac{5}{12} = \frac{5}{7}\)

Marking scheme

M1 for converting to improper fractions \(\frac{12}{7}\) and \(\frac{12}{5}\) and writing \(\frac{12}{7} \times \frac{5}{12}\)
A1 for \(\frac{5}{7}\) cao
Question 4 · short-answer
2 marks
The interior angle of a regular polygon is \(156^\circ\).

Calculate the number of sides of this polygon.
Show answer & marking scheme

Worked solution

Find the exterior angle of the regular polygon:
\(\text{Exterior angle} = 180^\circ - 156^\circ = 24^\circ\)

The sum of the exterior angles of any convex polygon is \(360^\circ\):
\(n = \frac{360^\circ}{24^\circ} = 15\)

Marking scheme

M1 for \(180 - 156 (= 24)\) or \(\frac{(n-2) \times 180}{n} = 156\) oe
A1 for \(15\)
Question 5 · short-answer
2 marks
Find the value of \(\left(\frac{125}{64}\right)^{-\frac{2}{3}}\).

Give your answer as a fraction in its simplest form.
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Worked solution

Apply index laws:
\(\left(\frac{125}{64}\right)^{-\frac{2}{3}} = \left(\frac{64}{125}\right)^{\frac{2}{3}}\)

Take the cube root and then square:
\(\sqrt[3]{\frac{64}{125}} = \frac{4}{5}\)
\(\left(\frac{4}{5}\right)^2 = \frac{16}{25}\)

Marking scheme

M1 for dealing with negative power or cube root, e.g. \(\left(\frac{64}{125}\right)^{\frac{2}{3}}\) or \(\left(\frac{5}{4}\right)^{-2}\) or \(\frac{4}{5}\) seen
A1 for \(\frac{16}{25}\)
Question 6 · short-answer
3 marks
A trapezium has parallel sides of lengths \((x + 3)\text{ cm}\) and \((2x - 1)\text{ cm}\).
The perpendicular distance between the parallel sides is \(6\text{ cm}\).
The area of the trapezium is \(51\text{ cm}^2\).

Work out the value of \(x\).
Show answer & marking scheme

Worked solution

The area of a trapezium is given by \(A = \frac{1}{2}(a + b)h\).

Substitute the given expressions:
\(51 = \frac{1}{2} \big((x + 3) + (2x - 1)\big) \times 6\)
\(51 = 3(3x + 2)\)
\(51 = 9x + 6\)
\(9x = 45\)
\(x = 5\)

Marking scheme

M1 for \(\frac{1}{2}\big((x+3) + (2x-1)\big) \times 6 = 51\) oe
M1 for simplifying correctly to \(9x + 6 = 51\) or \(3x + 2 = 17\)
A1 for \(5\)
Question 7 · short-answer
3 marks
\(A\), \(B\), \(C\) and \(D\) are points on the circumference of a circle.
Chord \(AC\) intersects chord \(BD\) at the point \(X\).
Angle \(BAC = 38^\circ\) and angle \(BXC = 82^\circ\).

Work out the size of angle \(ACD\).
Show answer & marking scheme

Worked solution

1. In triangle \(ABX\), angle \(AXB\) and angle \(BXC\) lie on a straight line:
\(\text{Angle } AXB = 180^\circ - 82^\circ = 98^\circ\)

2. Angles in triangle \(ABX\) sum to \(180^\circ\):
\(\text{Angle } ABD = 180^\circ - (98^\circ + 38^\circ) = 180^\circ - 136^\circ = 44^\circ\)

3. Angles in the same segment subtended by arc \(AD\) are equal:
\(\text{Angle } ACD = \text{angle } ABD = 44^\circ\)

Marking scheme

M1 for angle \(AXB = 180 - 82 (= 98^\circ)\) or using exterior angle \(82^\circ = 38^\circ + \text{angle } ABD\)
M1 for angle \(ABD = 44^\circ\)
A1 for \(44^\circ\)
Question 8 · short-answer
2 marks
Work out \((4.8 \times 10^7) \div (8 \times 10^{-3})\).

Give your answer in standard form.
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Worked solution

Divide the numerical coefficients and powers of 10 separately:
\(\frac{4.8 \times 10^7}{8 \times 10^{-3}} = \left(\frac{4.8}{8}\right) \times 10^{7 - (-3)}\)
\(= 0.6 \times 10^{10}\)

Convert to standard form \(A \times 10^n\) where \(1 \le A < 10\):
\(0.6 \times 10^{10} = 6 \times 10^9\)

Marking scheme

M1 for \(0.6 \times 10^{10}\) oe or \(\frac{4.8}{8} \times 10^{10}\)
A1 for \(6 \times 10^9\)
Question 9 · short_answer
3 marks
Work out \( 2\frac{1}{4} \div \left( \frac{5}{6} - \frac{1}{3} \right) \).

Give your answer as a mixed number in its simplest form.
Show answer & marking scheme

Worked solution

1. Evaluate the expression inside the brackets:
\[ \frac{5}{6} - \frac{1}{3} = \frac{5}{6} - \frac{2}{6} = \frac{3}{6} = \frac{1}{2} \]

2. Convert the mixed number to an improper fraction:
\[ 2\frac{1}{4} = \frac{9}{4} \]

3. Divide the fractions by multiplying by the reciprocal:
\[ \frac{9}{4} \div \frac{1}{2} = \frac{9}{4} \times \frac{2}{1} = \frac{18}{4} = \frac{9}{2} \]

4. Convert the result to a mixed number:
\[ \frac{9}{2} = 4\frac{1}{2} \]

Marking scheme

M1 for a correct method to subtract the fractions inside the bracket, e.g. \( \frac{5}{6} - \frac{2}{6} = \frac{3}{6} \) oe, or for converting \( 2\frac{1}{4} \) to \( \frac{9}{4} \)
M1 for multiplying by the reciprocal of their bracket, e.g. \( \frac{9}{4} \times \frac{2}{1} \) or \( \frac{9}{4} \times \frac{6}{3} \) oe
A1 for \( 4\frac{1}{2} \) (cao)
Question 10 · short_answer
3 marks
The exterior angles of a pentagon are \( x^\circ \), \( 2x^\circ \), \( (x + 20)^\circ \), \( (2x - 10)^\circ \) and \( 50^\circ \).

Find the value of \( x \).
Show answer & marking scheme

Worked solution

1. The sum of the exterior angles of any convex polygon is \( 360^\circ \).

2. Set up the equation:
\[ x + 2x + (x + 20) + (2x - 10) + 50 = 360 \]

3. Simplify the left-hand side:
\[ 6x + 60 = 360 \]

4. Solve for \( x \):
\[ 6x = 300 \]
\[ x = 50 \]

Marking scheme

M1 for equating the sum of the five given exterior angles to 360: \( x + 2x + (x + 20) + (2x - 10) + 50 = 360 \) oe
M1 for simplifying to the form \( 6x + 60 = 360 \) or \( 6x = 300 \)
A1 for 50
Question 11 · short-answer
4 marks
Simplify fully.
$$\frac{2x^2 - 5x - 12}{4x^2 - 9}$$
Show answer & marking scheme

Worked solution

1. Factorise the numerator by grouping or inspection:
$$2x^2 - 5x - 12 = 2x^2 - 8x + 3x - 12 = 2x(x - 4) + 3(x - 4) = (2x + 3)(x - 4)$$

2. Factorise the denominator using the difference of two squares:
$$4x^2 - 9 = (2x - 3)(2x + 3)$$

3. Cancel the common factor of \((2x + 3)\):
$$\frac{(2x + 3)(x - 4)}{(2x - 3)(2x + 3)} = \frac{x - 4}{2x - 3}$$

Marking scheme

M2 for \((2x + 3)(x - 4)\) (or M1 for \((2x + a)(x + b)\) where \(ab = -12\) or \(2b + a = -5\))
M1 for \((2x - 3)(2x + 3)\)
A1 for \(\frac{x - 4}{2x - 3}\)
Question 12 · short-answer
4 marks
Point \(A\) has coordinates \((1, -3)\) and point \(B\) has coordinates \((7, 5)\).

Find the equation of the perpendicular bisector of the line segment \(AB\).
Give your answer in the form \(y = mx + c\).
Show answer & marking scheme

Worked solution

1. Find the midpoint of \(AB\):
$$\text{Midpoint} = \left(\frac{1 + 7}{2}, \frac{-3 + 5}{2}\right) = (4, 1)$$

2. Calculate the gradient of the line segment \(AB\):
$$m_{AB} = \frac{5 - (-3)}{7 - 1} = \frac{8}{6} = \frac{4}{3}$$

3. Determine the gradient of the perpendicular bisector:
$$m_{\perp} = -\frac{1}{m_{AB}} = -\frac{3}{4}$$

4. Find the equation using the point \((4, 1)\):
$$y - y_1 = m(x - x_1) \implies y - 1 = -\frac{3}{4}(x - 4)$$
$$y - 1 = -\frac{3}{4}x + 3 \implies y = -\frac{3}{4}x + 4$$

Marking scheme

B1 for midpoint \((4, 1)\)
M1 for gradient of \(AB = \frac{8}{6} = \frac{4}{3}\)
M1 for perpendicular gradient \(-\frac{3}{4}\) (FT their gradient)
A1 for \(y = -\frac{3}{4}x + 4\) or \(y = -0.75x + 4\)
Question 13 · short-answer
3 marks
In triangle \(ABC\), \(AB = 6\text{ cm}\), angle \(ABC = 45^\circ\) and angle \(ACB = 30^\circ\).

Work out the exact length of \(AC\).
Give your answer in the form \(a\sqrt{b}\), where \(a\) and \(b\) are integers.
Show answer & marking scheme

Worked solution

1. Use the sine rule:
$$\frac{AC}{\sin(\angle ABC)} = \frac{AB}{\sin(\angle ACB)}$$
$$\frac{AC}{\sin 45^\circ} = \frac{6}{\sin 30^\circ}$$

2. Substitute the exact trigonometric values:
$$\sin 45^\circ = \frac{\sqrt{2}}{2}, \quad \sin 30^\circ = \frac{1}{2}$$

3. Solve for \(AC\):
$$AC = \frac{6 \times \frac{\sqrt{2}}{2}}{\frac{1}{2}} = 6\sqrt{2}\text{ cm}$$

Marking scheme

M1 for applying sine rule correctly: \(\frac{AC}{\sin 45^\circ} = \frac{6}{\sin 30^\circ}\)
B1 for both exact values stated: \(\sin 45^\circ = \frac{\sqrt{2}}{2}\) and \(\sin 30^\circ = \frac{1}{2}\)
A1 for \(6\sqrt{2}\)
Question 14 · short-answer
4 marks
(a) Write \(x^2 - 8x + 11\) in the form \((x - p)^2 + q\), where \(p\) and \(q\) are integers.
(b) Hence, solve the equation \(x^2 - 8x + 11 = 0\). Give your answers in the form \(a \pm \sqrt{b}\), where \(a\) and \(b\) are integers.
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Worked solution

(a) Completing the square:
$$x^2 - 8x + 11 = (x - 4)^2 - 4^2 + 11 = (x - 4)^2 - 16 + 11 = (x - 4)^2 - 5$$

(b) Using the completed square form:
$$(x - 4)^2 - 5 = 0$$
$$(x - 4)^2 = 5$$
$$x - 4 = \pm\sqrt{5}$$
$$x = 4 \pm \sqrt{5}$$

Marking scheme

(a) M1 for \((x - 4)^2 + k\)
A1 for \((x - 4)^2 - 5\)
(b) M1 for \((x - 4)^2 = 5\) or \(x - 4 = \pm\sqrt{5}\) (FT their \(p\) and \(q\))
A1 for \(x = 4 \pm \sqrt{5}\)
Question 15 · short-answer
4 marks
Given \(f(x) = 5 - 2x\) and \(g(x) = \frac{3x + 1}{4}\),

(a) Find \(f^{-1}(x)\).
(b) Work out the value of \(gf(2)\).
(c) Solve the equation \(g(x) = f(x)\).
Show answer & marking scheme

Worked solution

(a) Let \(y = 5 - 2x\):
$$2x = 5 - y \implies x = \frac{5 - y}{2}$$
$$f^{-1}(x) = \frac{5 - x}{2}$$

(b) First evaluate \(f(2)\):
$$f(2) = 5 - 2(2) = 1$$
Then evaluate \(g(1)\):
$$g(1) = \frac{3(1) + 1}{4} = \frac{4}{4} = 1$$

(c) Set \(g(x) = f(x)\):
$$\frac{3x + 1}{4} = 5 - 2x$$
$$3x + 1 = 4(5 - 2x)$$
$$3x + 1 = 20 - 8x$$
$$11x = 19 \implies x = \frac{19}{11}$$

Marking scheme

(a) B1 for \(f^{-1}(x) = \frac{5 - x}{2}\) or \(2.5 - 0.5x\)
(b) B1 for \(1\)
(c) M1 for correct clearance of fraction: \(3x + 1 = 4(5 - 2x)\)
A1 for \(x = \frac{19}{11}\) or \(1\frac{8}{11}\)
Question 16 · short-answer
3 marks
Solve the equation
$$2\sin x + \sqrt{3} = 0$$
for \(0^\circ \le x \le 360^\circ\).
Show answer & marking scheme

Worked solution

1. Rearrange to find \(\sin x\):
$$2\sin x = -\sqrt{3} \implies \sin x = -\frac{\sqrt{3}}{2}$$

2. Find the reference angle:
$$\sin \alpha = \frac{\sqrt{3}}{2} \implies \alpha = 60^\circ$$

3. Since \(\sin x\) is negative, solutions lie in the 3rd and 4th quadrants:
$$\text{Quadrant III: } x = 180^\circ + 60^\circ = 240^\circ$$
$$\text{Quadrant IV: } x = 360^\circ - 60^\circ = 300^\circ$$

Marking scheme

M1 for \(\sin x = -\frac{\sqrt{3}}{2}\)
B1 for reference angle \(60^\circ\) or one correct angle (\(240^\circ\) or \(300^\circ\))
A1 for both \(x = 240^\circ\) and \(x = 300^\circ\) and no extra solutions in range
Question 17 · short-answer
4 marks
Solve the simultaneous equations.
$$x - y = 3$$
$$x^2 + y^2 = 29$$
Show all your working.
Show answer & marking scheme

Worked solution

1. Express \(y\) in terms of \(x\) from the linear equation:
$$y = x - 3$$

2. Substitute into the second equation:
$$x^2 + (x - 3)^2 = 29$$
$$x^2 + (x^2 - 6x + 9) = 29$$
$$2x^2 - 6x - 20 = 0$$

3. Simplify the quadratic equation by dividing by 2:
$$x^2 - 3x - 10 = 0$$

4. Factorise:
$$(x - 5)(x + 2) = 0$$
So \(x = 5\) or \(x = -2\).

5. Find the corresponding \(y\)-values:
When \(x = 5\), \(y = 5 - 3 = 2\).
When \(x = -2\), \(y = -2 - 3 = -5\).

Marking scheme

M1 for correct substitution of linear expression into non-linear: \(x^2 + (x - 3)^2 = 29\) or \((y + 3)^2 + y^2 = 29\)
M1 for simplifying to a 3-term quadratic: \(2x^2 - 6x - 20 = 0\) or \(x^2 - 3x - 10 = 0\)
A1 for finding both correct values of one variable: \(x = 5, x = -2\) (or \(y = 2, y = -5\))
A1 for both complete pairs: \(x = 5, y = 2\) and \(x = -2, y = -5\)
Question 18 · short-answer
4 marks
A curve has equation \(y = 2x^3 - 9x^2 + 12x - 5\).

(a) Find \(\frac{\mathrm{d}y}{\mathrm{d}x}\).
(b) Find the coordinates of the two stationary points on the curve.
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Worked solution

(a) Differentiating term by term:
$$\frac{\mathrm{d}y}{\mathrm{d}x} = 2(3x^2) - 9(2x) + 12(1) - 0 = 6x^2 - 18x + 12$$

(b) At stationary points, \(\frac{\mathrm{d}y}{\mathrm{d}x} = 0\):
$$6x^2 - 18x + 12 = 0$$
$$6(x^2 - 3x + 2) = 0$$
$$6(x - 1)(x - 2) = 0$$
So \(x = 1\) or \(x = 2\).

Substitute the \(x\)-values back into the curve equation:
When \(x = 1\):
$$y = 2(1)^3 - 9(1)^2 + 12(1) - 5 = 2 - 9 + 12 - 5 = 0$$
Stationary point: \((1, 0)\).

When \(x = 2\):
$$y = 2(2)^3 - 9(2)^2 + 12(2) - 5 = 16 - 36 + 24 - 5 = -1$$
Stationary point: \((2, -1)\).

Marking scheme

(a) B1 for any two correct non-zero differentiated terms, B1 for fully correct derivative \(6x^2 - 18x + 12\)
(b) M1 for setting their derivative \(= 0\) and solving for \(x\) (obtaining \(x = 1\) and \(x = 2\))
A1 for both coordinates \((1, 0)\) and \((2, -1)\)
Question 19 · open-response
4 marks
The coordinates of point \(A\) are \((-2, 7)\) and the coordinates of point \(B\) are \((6, 1)\).

Find the equation of the perpendicular bisector of the line segment \(AB\).
Give your answer in the form \(y = mx + c\).
Show answer & marking scheme

Worked solution

1. Find the midpoint, \(M\), of line segment \(AB\):
\[ M = \left(\frac{-2 + 6}{2}, \frac{7 + 1}{2}\right) = (2, 4) \]

2. Find the gradient of line \(AB\):
\[ m_{AB} = \frac{1 - 7}{6 - (-2)} = \frac{-6}{8} = -\frac{3}{4} \]

3. The perpendicular gradient \(m_{\perp}\) is the negative reciprocal of \(m_{AB}\):
\[ m_{\perp} = -\frac{1}{-\frac{3}{4}} = \frac{4}{3} \]

4. Use the point-slope form with midpoint \((2, 4)\):
\[ y - 4 = \frac{4}{3}(x - 2) \]
\[ y = \frac{4}{3}x - \frac{8}{3} + 4 \]
\[ y = \frac{4}{3}x + \frac{4}{3} \]

Marking scheme

M1: for finding the midpoint of \(AB\) as \((2, 4)\)
M1: for finding the gradient of \(AB\) as \(-\frac{3}{4}\) oe
M1: for using the perpendicular gradient \(m_{\perp} = \frac{4}{3}\) with their midpoint in \(y - y_1 = m(x - x_1)\) or \(y = mx + c\)
A1: for \(y = \frac{4}{3}x + \frac{4}{3}\) oe (e.g. \(y = 1\frac{1}{3}x + 1\frac{1}{3}\))
Question 20 · open-response
4 marks
In triangle \(ABC\), \(AB = 5\text{ cm}\), \(BC = 8\text{ cm}\) and angle \(ABC = 60^\circ\).

(a) Work out the exact area of triangle \(ABC\).
Give your answer in the form \(k\sqrt{3}\), where \(k\) is an integer.

(b) Work out the length of \(AC\).
Show answer & marking scheme

Worked solution

(a) Use the area formula \(\text{Area} = \frac{1}{2}ab\sin C\):
\[ \text{Area} = \frac{1}{2} \times 5 \times 8 \times \sin 60^\circ \]
Since \(\sin 60^\circ = \frac{\sqrt{3}}{2}\):
\[ \text{Area} = 20 \times \frac{\sqrt{3}}{2} = 10\sqrt{3}\text{ cm}^2 \]

(b) Use the cosine rule \(b^2 = a^2 + c^2 - 2ac\cos B\):
\[ AC^2 = 5^2 + 8^2 - 2(5)(8)\cos 60^\circ \]
Since \(\cos 60^\circ = \frac{1}{2}\):
\[ AC^2 = 25 + 64 - 80\left(\frac{1}{2}\right) \]
\[ AC^2 = 89 - 40 = 49 \]
\[ AC = \sqrt{49} = 7\text{ cm} \]

Marking scheme

(a)
M1: for \(\frac{1}{2} \times 5 \times 8 \times \sin 60^\circ\) or stating \(\sin 60^\circ = \frac{\sqrt{3}}{2}\)
A1: for \(10\sqrt{3}\)

(b)
M1: for \(5^2 + 8^2 - 2(5)(8)\cos 60^\circ\) with \(\cos 60^\circ = \frac{1}{2}\) substituted correctly
A1: for \(7\)
Question 21 · question
5.125 marks
A curve has equation \( y = \frac{1}{3}x^3 - 2x^2 + 3x + 4 \).

(a) Find the coordinates of the two stationary points on the curve.
(b) By determining the nature of each stationary point, state which is a local maximum and which is a local minimum. Show all your working.
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Worked solution

(a) \(\frac{\mathrm{d}y}{\mathrm{d}x} = x^2 - 4x + 3\).
Setting \(\frac{\mathrm{d}y}{\mathrm{d}x} = 0\):
\(x^2 - 4x + 3 = 0 \implies (x - 1)(x - 3) = 0\), so \(x = 1\) or \(x = 3\).
When \(x = 1\), \(y = \frac{1}{3}(1)^3 - 2(1)^2 + 3(1) + 4 = \frac{1}{3} - 2 + 3 + 4 = 5\frac{1}{3} = \frac{16}{3}\).
When \(x = 3\), \(y = \frac{1}{3}(27) - 2(9) + 3(3) + 4 = 9 - 18 + 9 + 4 = 4\).
The stationary points are \((1, \frac{16}{3})\) and \((3, 4)\).

(b) \(\frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 2x - 4\).
At \(x = 1\), \(\frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 2(1) - 4 = -2 < 0\), hence \((1, \frac{16}{3})\) is a maximum.
At \(x = 3\), \(\frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 2(3) - 4 = 2 > 0\), hence \((3, 4)\) is a minimum.

Marking scheme

M1: Correct derivative \(x^2 - 4x + 3\)
M1: Equating derivative to 0 and solving to find \(x = 1, x = 3\)
A1: Correct \(y\)-values \(\frac{16}{3}\) and \(4\)
M1: Method to determine nature (e.g. correct second derivative \(2x - 4\) or sign testing of gradient)
A1: Correct identification of maximum at \((1, \frac{16}{3})\) and minimum at \((3, 4)\) with full justification
Question 22 · question
5.125 marks
Solve the equation
\[ \frac{3}{2x - 1} - \frac{2}{x + 2} = 1 \]
Show all your working and give your answers in the exact form \( a \pm \sqrt{b} \), where \( a \) and \( b \) are integers.
Show answer & marking scheme

Worked solution

Multiply the entire equation by \((2x - 1)(x + 2)\):
\(3(x + 2) - 2(2x - 1) = 1(2x - 1)(x + 2)\)
Expand both sides:
\(3x + 6 - 4x + 2 = 2x^2 + 4x - x - 2\)
\(-x + 8 = 2x^2 + 3x - 2\)
Rearrange to form a quadratic equation:
\(2x^2 + 4x - 10 = 0\)
Divide by 2:
\(x^2 + 2x - 5 = 0\)
Apply the quadratic formula or complete the square:
\((x + 1)^2 - 1 - 5 = 0 \implies (x + 1)^2 = 6\)
\(x + 1 = \pm \sqrt{6} \implies x = -1 \pm \sqrt{6}\).

Marking scheme

M1: Multiplies by common denominator to obtain \(3(x + 2) - 2(2x - 1) = (2x - 1)(x + 2)\)
M1: Correct expansion of all brackets
M1: Rearranges into standard quadratic form \(2x^2 + 4x - 10 = 0\) or \(x^2 + 2x - 5 = 0\)
M1: Applies quadratic formula or completes the square correctly on their 3-term quadratic
A1: Correct exact final answer \(-1 \pm \sqrt{6}\) (or \(x = -1 + \sqrt{6}\), \(x = -1 - \sqrt{6}\))
Question 23 · question
5.125 marks
In triangle \( ABC \), \( AB = (2\sqrt{3} - 1)\text{ cm} \), \( BC = (2\sqrt{3} + 1)\text{ cm} \), and angle \( ABC = 60^\circ \).

(a) Show that the exact area of triangle \( ABC \) is \( \frac{11\sqrt{3}}{4}\text{ cm}^2 \).
(b) Find the exact length of \( AC \), giving your answer in the form \( \sqrt{k} \), where \( k \) is an integer.
Show answer & marking scheme

Worked solution

(a) \(\text{Area} = \frac{1}{2} a c \sin B = \frac{1}{2}(2\sqrt{3} - 1)(2\sqrt{3} + 1)\sin 60^\circ\).
\((2\sqrt{3} - 1)(2\sqrt{3} + 1) = (2\sqrt{3})^2 - 1^2 = 12 - 1 = 11\).
Since \(\sin 60^\circ = \frac{\sqrt{3}}{2}\):
\(\text{Area} = \frac{1}{2} \times 11 \times \frac{\sqrt{3}}{2} = \frac{11\sqrt{3}}{4}\text{ cm}^2\).

(b) Using the cosine rule:
\(AC^2 = AB^2 + BC^2 - 2(AB)(BC)\cos 60^\circ\)
\(AB^2 = (2\sqrt{3} - 1)^2 = 12 - 4\sqrt{3} + 1 = 13 - 4\sqrt{3}\)
\(BC^2 = (2\sqrt{3} + 1)^2 = 12 + 4\sqrt{3} + 1 = 13 + 4\sqrt{3}\)
\(AB^2 + BC^2 = (13 - 4\sqrt{3}) + (13 + 4\sqrt{3}) = 26\)
\(2(AB)(BC)\cos 60^\circ = 2(11)\left(\frac{1}{2}\right) = 11\)
\(AC^2 = 26 - 11 = 15\)
\(AC = \sqrt{15}\text{ cm}\).

Marking scheme

M1 (part a): Uses \(\frac{1}{2} a c \sin 60^\circ\) with \(\sin 60^\circ = \frac{\sqrt{3}}{2}\)
A1 (part a): Expands \((2\sqrt{3}-1)(2\sqrt{3}+1) = 11\) correctly to reach \(\frac{11\sqrt{3}}{4}\)
M1 (part b): Correct substitution into cosine rule \(AC^2 = (2\sqrt{3}-1)^2 + (2\sqrt{3}+1)^2 - 2(11)\cos 60^\circ\)
M1 (part b): Correct expansions of both brackets and substitution of \(\cos 60^\circ = \frac{1}{2}\)
A1 (part b): \(\sqrt{15}\) correctly derived with all intermediate steps shown
Question 24 · question
5.125 marks
In a triangle \( OAB \), \( \vec{OA} = \mathbf{a} \) and \( \vec{OB} = \mathbf{b} \).
\( P \) is the point on \( AB \) such that \( AP : PB = 2 : 3 \).
\( Q \) is the point on \( OB \) such that \( OQ : QB = 3 : 2 \).

(a) Express \( \vec{OP} \) and \( \vec{AQ} \) in terms of \( \mathbf{a} \) and \( \mathbf{b} \), giving each vector in its simplest form.
(b) The line segments \( OP \) and \( AQ \) intersect at the point \( X \).
Given that \( \vec{OX} = \lambda \vec{OP} \) and \( \vec{AX} = \mu \vec{AQ} \), find the exact values of the scalars \( \lambda \) and \( \mu \).
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Worked solution

(a) \(\vec{AB} = \mathbf{b} - \mathbf{a}\).
\(\vec{OP} = \vec{OA} + \frac{2}{5}\vec{AB} = \mathbf{a} + \frac{2}{5}(\mathbf{b} - \mathbf{a}) = \frac{3}{5}\mathbf{a} + \frac{2}{5}\mathbf{b}\).
\(\vec{OQ} = \frac{3}{5}\mathbf{b}\), so \(\vec{AQ} = \vec{AO} + \vec{OQ} = -\mathbf{a} + \frac{3}{5}\mathbf{b}\).

(b) \(\vec{OX} = \lambda \vec{OP} = \frac{3}{5}\lambda \mathbf{a} + \frac{2}{5}\lambda \mathbf{b}\).
Also, \(\vec{OX} = \vec{OA} + \vec{AX} = \mathbf{a} + \mu \vec{AQ} = \mathbf{a} + \mu(-\mathbf{a} + \frac{3}{5}\mathbf{b}) = (1 - \mu)\mathbf{a} + \frac{3}{5}\mu \mathbf{b}\).
Equating coefficients of \(\mathbf{a}\) and \(\mathbf{b}\):
(1) \(\frac{3}{5}\lambda = 1 - \mu \implies 3\lambda + 5\mu = 5\)
(2) \(\frac{2}{5}\lambda = \frac{3}{5}\mu \implies 2\lambda = 3\mu \implies \lambda = \frac{3}{2}\mu\)
Substitute into (1):
\(3\left(\frac{3}{2}\mu\right) + 5\mu = 5 \implies \frac{9}{2}\mu + \frac{10}{2}\mu = 5 \implies \frac{19}{2}\mu = 5 \implies \mu = \frac{10}{19}\).
\(\lambda = \frac{3}{2}\left(\frac{10}{19}\right) = \frac{15}{19}\).

Marking scheme

B1: Correct \(\vec{OP} = \frac{3}{5}\mathbf{a} + \frac{2}{5}\mathbf{b}\)
B1: Correct \(\vec{AQ} = -\mathbf{a} + \frac{3}{5}\mathbf{b}\)
M1: Sets up two vector paths for \(\vec{OX}\) in terms of \(\lambda\) and \(\mu\)
M1: Equates coefficients to form two simultaneous equations in \(\lambda\) and \(\mu\)
A1: Correct values \(\lambda = \frac{15}{19}\) and \(\mu = \frac{10}{19}\)
Question 25 · question
5.125 marks
The functions \( \mathrm{f}(x) \) and \( \mathrm{g}(x) \) are defined by
\[ \mathrm{f}(x) = \frac{2x + 3}{x - 4}, \quad x \ne 4 \]
\[ \mathrm{g}(x) = 3x - 1 \]

(a) Find an expression for \( \mathrm{f}^{-1}(x) \).
(b) Solve the equation \( \mathrm{g}(\mathrm{f}(x)) = 8 \).
(c) Solve the equation \( \mathrm{f}(x) = \mathrm{f}^{-1}(x) \), giving your answers in the exact form \( a \pm b\sqrt{c} \).
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Worked solution

(a) Let \(y = \frac{2x + 3}{x - 4}\).
\(y(x - 4) = 2x + 3 \implies yx - 4y = 2x + 3\)
\(yx - 2x = 4y + 3 \implies x(y - 2) = 4y + 3\)
\(x = \frac{4y + 3}{y - 2}\)
So \(\mathrm{f}^{-1}(x) = \frac{4x + 3}{x - 2}\).

(b) \(\mathrm{g}(\mathrm{f}(x)) = 3\left(\frac{2x + 3}{x - 4}\right) - 1 = 8\)
\(3\left(\frac{2x + 3}{x - 4}\right) = 9 \implies \frac{2x + 3}{x - 4} = 3\)
\(2x + 3 = 3(x - 4) \implies 2x + 3 = 3x - 12\)
\(x = 15\).

(c) \(\frac{2x + 3}{x - 4} = \frac{4x + 3}{x - 2}\)
\((2x + 3)(x - 2) = (4x + 3)(x - 4)\)
\(2x^2 - x - 6 = 4x^2 - 13x - 12\)
\(2x^2 - 12x - 6 = 0 \implies x^2 - 6x - 3 = 0\)
Using the quadratic formula:
\(x = \frac{6 \pm \sqrt{(-6)^2 - 4(1)(-3)}}{2} = \frac{6 \pm \sqrt{36 + 12}}{2} = \frac{6 \pm \sqrt{48}}{2} = \frac{6 \pm 4\sqrt{3}}{2} = 3 \pm 2\sqrt{3}\).

Marking scheme

M1 (part a): Correct rearrangement steps to isolate \(x\): \(yx - 2x = 4y + 3\)
A1 (part a): \(\mathrm{f}^{-1}(x) = \frac{4x + 3}{x - 2}\)
M1 (part b): Equating \(3\mathrm{f}(x) - 1 = 8\) and solving to obtain \(x = 15\)
M1 (part c): Equates \(\mathrm{f}(x) = \mathrm{f}^{-1}(x)\) and simplifies to \(x^2 - 6x - 3 = 0\) (or \(2x^2 - 12x - 6 = 0\))
A1 (part c): Fully simplified exact answers \(3 \pm 2\sqrt{3}\)
Question 26 · question
5.125 marks
A solid cone has base radius \( r \) and slant height \( 3r \).
A solid sphere has radius \( R \).

(a) Show that the total surface area of the cone is \( 4\pi r^2 \).
(b) The total surface area of the cone is equal to the surface area of the sphere. Show that \( R = r \).
(c) Find the ratio of the volume of the cone to the volume of the sphere.
Give your answer in the form \( \sqrt{a} : b \), where \( a \) and \( b \) are integers.
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Worked solution

(a) Total surface area of a cone = \(\pi r^2 + \pi r l\).
With \(l = 3r\):
\(\text{Total surface area} = \pi r^2 + \pi r(3r) = \pi r^2 + 3\pi r^2 = 4\pi r^2\).

(b) Surface area of a sphere = \(4\pi R^2\).
Equating surface areas: \(4\pi R^2 = 4\pi r^2 \implies R^2 = r^2 \implies R = r\) (since \(R, r > 0\)).

(c) Height of the cone, \(h = \sqrt{l^2 - r^2} = \sqrt{(3r)^2 - r^2} = \sqrt{9r^2 - r^2} = \sqrt{8r^2} = 2\sqrt{2}r\).
\(\text{Volume of cone} = \frac{1}{3}\pi r^2 h = \frac{1}{3}\pi r^2 (2\sqrt{2}r) = \frac{2\sqrt{2}}{3}\pi r^3\).
\(\text{Volume of sphere} = \frac{4}{3}\pi R^3 = \frac{4}{3}\pi r^3\).
Ratio \(\text{Volume of cone} : \text{Volume of sphere} = \frac{2\sqrt{2}}{3}\pi r^3 : \frac{4}{3}\pi r^3 = 2\sqrt{2} : 4 = \sqrt{2} : 2\).

Marking scheme

B1 (part a): Correct addition of base area and curved surface area: \(\pi r^2 + \pi r(3r) = 4\pi r^2\)
B1 (part b): Equating \(4\pi R^2 = 4\pi r^2\) and concluding \(R = r\)
M1 (part c): Finds vertical height of cone \(h = \sqrt{8}r = 2\sqrt{2}r\)
M1 (part c): Writes correct volume formulas: \(\frac{1}{3}\pi r^2(2\sqrt{2}r)\) and \(\frac{4}{3}\pi r^3\)
A1 (part c): Simplifies ratio to exact form \(\sqrt{2} : 2\)
Question 27 · question
5.125 marks
NOT TO SCALE
\( A, B, C \), and \( D \) are points on the circumference of a circle, centre \( O \).
\( TA \) and \( TB \) are tangents to the circle from the external point \( T \).
Angle \( ATB = 44^\circ \).

(a) Find angle \( AOB \). Give a geometrical reason for your answer.
(b) Find angle \( ADB \). Give a geometrical reason for your answer.
(c) Given that \( AC \) is a diameter of the circle, find:
(i) angle \( ABC \),
(ii) angle \( CAB \).
Show answer & marking scheme

Worked solution

(a) \(\angle OAT = 90^\circ\) and \(\angle OBT = 90^\circ\) because the angle between a tangent and a radius is \(90^\circ\).
In quadrilateral \(OATB\), the sum of angles is \(360^\circ\):
\(\angle AOB = 360^\circ - (90^\circ + 90^\circ + 44^\circ) = 180^\circ - 44^\circ = 136^\circ\).

(b) \(\angle ADB = \frac{1}{2} \times \angle AOB = \frac{1}{2} \times 136^\circ = 68^\circ\) because the angle subtended at the centre is twice the angle subtended at the circumference.

(c)(i) \(\angle ABC = 90^\circ\) because the angle in a semicircle is \(90^\circ\).

(c)(ii) In the isosceles triangle \(OAB\) (where \(OA = OB\) are radii):
\(\angle OAB = \frac{180^\circ - 136^\circ}{2} = \frac{44^\circ}{2} = 22^\circ\).
Since \(O\) lies on the line segment \(AC\), \(\angle CAB = \angle OAB = 22^\circ\).

Marking scheme

B1: \(136^\circ\) with valid reason (tangent-radius is \(90^\circ\) / angles in quadrilateral sum to \(360^\circ\))
B1: \(68^\circ\) with valid reason (angle at centre is twice angle at circumference)
B1: \(\angle ABC = 90^\circ\) (angle in semicircle is \(90^\circ\))
M1: Method to find \(\angle CAB\), e.g. using isosceles triangle \(OAB\): \(\frac{180 - 136}{2}\) or \(90 - 68\)
A1: \(\angle CAB = 22^\circ\)
Question 28 · question
5.125 marks
The points \( A \) and \( B \) have coordinates \( (-3, 5) \) and \( (5, 1) \) respectively.

(a) Find the equation of the perpendicular bisector of the line segment \( AB \).
Give your answer in the form \( ax + by + c = 0 \), where \( a, b, \) and \( c \) are integers.
(b) The perpendicular bisector intersects the line \( 2x + y = 9 \) at the point \( P \).
Find the coordinates of \( P \).
(c) Find the exact distance from the origin \( (0, 0) \) to \( P \).
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Worked solution

(a) Midpoint of \( AB = \left(\frac{-3 + 5}{2}, \frac{5 + 1}{2}\right) = (1, 3) \).
Gradient of \( AB = \frac{1 - 5}{5 - (-3)} = \frac{-4}{8} = -\frac{1}{2} \).
Gradient of the perpendicular bisector = \(-\frac{1}{-\frac{1}{2}} = 2\).
Equation of the line passing through \((1, 3)\) with gradient 2:
\(y - 3 = 2(x - 1) \implies y - 3 = 2x - 2 \implies 2x - y + 1 = 0\).

(b) We have the system of linear equations:
(1) \(y = 2x + 1\)
(2) \(2x + y = 9\)
Substitute (1) into (2):
\(2x + (2x + 1) = 9 \implies 4x + 1 = 9 \implies 4x = 8 \implies x = 2\).
\(y = 2(2) + 1 = 5\).
Thus, \(P = (2, 5)\).

(c) Distance from origin \(O(0, 0)\) to \(P(2, 5)\):
\(OP = \sqrt{(2 - 0)^2 + (5 - 0)^2} = \sqrt{2^2 + 5^2} = \sqrt{4 + 25} = \sqrt{29}\).

Marking scheme

M1 (part a): Calculates midpoint \((1, 3)\) and gradient \(-\frac{1}{2}\)
M1 (part a): Uses perpendicular gradient \(2\) with midpoint in straight line equation
A1 (part a): \(2x - y + 1 = 0\) (or any integer multiple equivalent such as \(-2x + y - 1 = 0\))
M1 (part b): Solves simultaneous linear equations to find \(P(2, 5)\)
A1 (part c): Correct exact distance \(\sqrt{29}\)

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Practice This Topic

Paper 4 (Extended Calculator)

Answer all questions. Scientific calculators should be used where appropriate. Give answers to 3 significant figures or 1 decimal place for angles.
21 Question · 99 marks
Question 1 · Numeric
3.125 marks
A piece of heavy machinery loses value at a rate of 4.5% compound per year.
Its initial value is $18\,500.

Calculate the value of the machinery at the end of 6 years.
Give your answer correct to the nearest dollar.
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Worked solution

Using the compound decay formula:
\(V = P\left(1 - \frac{r}{100}\right)^n\)
\(V = 18\,500 \times (1 - 0.045)^6\)
\(V = 18\,500 \times (0.955)^6\)
\(V = 18\,500 \times 0.7584168... = 14\,030.71...\)

Rounding to the nearest dollar gives $14\,031.

Marking scheme

M1 for \(18\,500 \times (1 - 0.045)^6\) or \(18\,500 \times 0.955^6\) oe
A1 for answer in range \([14\,030.7, 14\,031]\)
B1 for rounding correctly to the nearest integer (14\,031) dep on at least M1 scored
Question 2 · Numeric
3.125 marks
In triangle \(ABC\), \(AB = 7.4\text{ cm}\), \(AC = 9.8\text{ cm}\) and angle \(BAC = 53^\circ\).

Calculate the area of triangle \(ABC\).
Show answer & marking scheme

Worked solution

Use the formula for the area of a non-right-angled triangle:
\(\text{Area} = \frac{1}{2}ab\sin(C)\)
\(\text{Area} = \frac{1}{2} \times 7.4 \times 9.8 \times \sin(53^\circ)\)
\(\text{Area} = 36.26 \times \sin(53^\circ) = 28.9585...\text{ cm}^2\)

Rounding to 3 significant figures gives \(29.0\text{ cm}^2\).

Marking scheme

M2 for \(\frac{1}{2} \times 7.4 \times 9.8 \times \sin(53^\circ)\) (or M1 for \(\frac{1}{2} \times 7.4 \times 9.8 \times \sin(\dots)\))
A1 for 29.0 or 28.95 to 28.96
Question 3 · Numeric
3.125 marks
A sector of a circle of radius \(8.5\text{ cm}\) has a sector angle of \(132^\circ\).

Calculate the total perimeter of the sector.
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Worked solution

First, calculate the arc length of the sector:
\(\text{Arc length} = \frac{\theta}{360} \times 2\pi r = \frac{132}{360} \times 2 \times \pi \times 8.5 = 19.5826...\text{ cm}\)

Then, add the two radii to find the total perimeter:
\(\text{Perimeter} = \text{Arc length} + 2r\)
\(\text{Perimeter} = 19.5826... + 2 \times 8.5 = 19.5826... + 17 = 36.5826...\text{ cm}\)

Rounding to 3 significant figures gives \(36.6\text{ cm}\).

Marking scheme

M1 for \(\frac{132}{360} \times 2 \times \pi \times 8.5\) oe (arc length \(= 19.58...\))
M1 for arc length \(+ 2 \times 8.5\)
A1 for 36.6 or 36.58 to 36.59
Question 4 · Numeric
3.125 marks
Two solid ornamental vases are mathematically similar.
The height of the smaller vase is \(14\text{ cm}\) and the height of the larger vase is \(21\text{ cm}\).
The volume of the smaller vase is \(680\text{ cm}^3\).

Calculate the volume of the larger vase.
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Worked solution

Find the linear scale factor:
\(k = \frac{21}{14} = 1.5\)

The volume scale factor is \(k^3 = 1.5^3 = 3.375\).

Calculate the volume of the larger vase:
\(\text{Volume} = 680 \times 3.375 = 2295\text{ cm}^3\).

Marking scheme

M1 for linear scale factor \(\frac{21}{14}\) or \(\frac{14}{21}\) oe
M1 for volume scale factor \(\left(\frac{21}{14}\right)^3\) or \(1.5^3\) (3.375)
A1 for 2295
Question 5 · Numeric
3.125 marks
The equation of a straight line \(L\) is \(2y = 5x - 8\).

Find the gradient of a line that is perpendicular to line \(L\).
Show answer & marking scheme

Worked solution

Rearrange the equation of line \(L\) into the form \(y = mx + c\):
\(y = \frac{5}{2}x - 4\)

So the gradient of line \(L\) is \(m_1 = \frac{5}{2} = 2.5\).

For perpendicular lines, \(m_1 \times m_2 = -1\):
\(m_2 = -\frac{1}{2.5} = -\frac{2}{5} = -0.4\).

Marking scheme

M1 for finding the gradient of \(L\) as \(\frac{5}{2}\) or 2.5
M1 for using \(m_1 \times m_2 = -1\) or \(-\frac{1}{m}\)
A1 for \(-\frac{2}{5}\) or \(-0.4\)
Question 6 · Numeric
3.125 marks
The length of a rectangular floor is \(3.4\text{ m}\), correct to 1 decimal place.
The width of the floor is \(2.15\text{ m}\), correct to 2 decimal places.

Calculate the upper bound for the area of the floor.
Give your answer to 3 significant figures.
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Worked solution

Find the upper bounds for the measurements:
Upper bound for length \(= 3.4 + 0.05 = 3.45\text{ m}\)
Upper bound for width \(= 2.15 + 0.005 = 2.155\text{ m}\)

Calculate the upper bound for the area:
\(\text{Upper Bound for Area} = 3.45 \times 2.155 = 7.43475\text{ m}^2\)

Rounding to 3 significant figures gives \(7.43\text{ m}^2\).

Marking scheme

B1 for length upper bound \(3.45\)
B1 for width upper bound \(2.155\)
M1 for multiplying their upper bound length by their upper bound width
A1 for 7.43 or exact 7.43475
Question 7 · Numeric
3.125 marks
A solid metal sphere has a radius of \(4.2\text{ cm}\).

Calculate the surface area of the sphere.
Show answer & marking scheme

Worked solution

Use the formula for the surface area of a sphere:
\(A = 4\pi r^2\)
\(A = 4 \times \pi \times 4.2^2\)
\(A = 4 \times \pi \times 17.64 = 70.56\pi\)
\(A = 221.6707...\text{ cm}^2\)

Rounding to 3 significant figures gives \(222\text{ cm}^2\).

Marking scheme

M1 for substitution of \(r = 4.2\) into \(4\pi r^2\)
A1 for answer in range \([221.6, 222]\) or \(70.56\pi\)
Question 8 · Numeric
3.125 marks
A vertical communication pole \(PQ\) of height \(18.6\text{ m}\) stands on horizontal ground.
A support cable runs from the top of the pole \(P\) to a point on the ground \(R\).
The distance \(QR\) along the ground is \(12.4\text{ m}\).

Calculate the angle of elevation of \(P\) from \(R\).
Show answer & marking scheme

Worked solution

In the right-angled triangle \(PQR\), with right angle at \(Q\):
\(\tan(\angle PRQ) = \frac{\text{opposite}}{\text{adjacent}} = \frac{PQ}{QR}\)
\(\tan(\angle PRQ) = \frac{18.6}{12.4} = 1.5\)
\(\angle PRQ = \arctan(1.5) = 56.3099...^\circ\)

Rounding to 1 decimal place gives \(56.3^\circ\).

Marking scheme

M1 for \(\tan(\theta) = \frac{18.6}{12.4}\) oe
M1 for \(\arctan(1.5)\) oe
A1 for 56.3 or 56.30 to 56.31
Question 9 · structured
5 marks
The diagram shows a triangular field \(PQR\).
\(PQ = 74\text{ m}\), \(QR = 115\text{ m}\) and angle \(PQR = 64^\circ\).

(a) Calculate the length of the boundary \(PR\). [3]

(b) Calculate the shortest distance from the point \(Q\) to the boundary \(PR\). [2]
Show answer & marking scheme

Worked solution

(a) Using the cosine rule on triangle \(PQR\):
\[PR^2 = PQ^2 + QR^2 - 2(PQ)(QR)\cos(\angle PQR)\]
\[PR^2 = 74^2 + 115^2 - 2(74)(115)\cos(64^\circ)\]
\[PR^2 = 5476 + 13225 - 17020 \times 0.438371...\]
\[PR^2 = 18701 - 7461.077...\]
\[PR^2 = 11239.92...\]
\[PR = \sqrt{11239.92...} \approx 106.018...\text{ m}\]
To 3 significant figures, \(PR = 106\text{ m}\).

(b) Area of triangle \(PQR\):
\[\text{Area} = \frac{1}{2} \times 74 \times 115 \times \sin(64^\circ) = 4255 \times 0.898794... \approx 3824.37\text{ m}^2\]
The shortest distance \(h\) is the perpendicular height from \(Q\) to \(PR\):
\[\text{Area} = \frac{1}{2} \times PR \times h\]
\[3824.37 = \frac{1}{2} \times 106.018 \times h\]
\[h = \frac{2 \times 3824.37}{106.018} \approx 72.146...\text{ m}\]
To 3 significant figures, \(h = 72.1\text{ m}\).

Marking scheme

(a)
M1 for correct implicit cosine rule statement: \(74^2 + 115^2 - 2(74)(115)\cos(64^\circ)\)
A1 for \(11239.9...\) or \(11240\)
A1 for 106 or 106.0...

(b)
M1 for \(0.5 \times 74 \times 115 \times \sin(64^\circ)\) or \(0.5 \times 106.0... \times h = \text{Area}\)
A1 for 72.1 or 72.14...
Question 10 · structured
5 marks
The equation of a curve is \(y = 2x^3 - 9x^2 + 12x - 5\).

(a) Find \(\frac{\mathrm{d}y}{\mathrm{d}x}\). [2]

(b) Find the coordinates of the two stationary points on the curve and determine whether each is a maximum or a minimum. Show how you decide. [3]
Show answer & marking scheme

Worked solution

(a)
\[\frac{\mathrm{d}y}{\mathrm{d}x} = 2(3)x^2 - 9(2)x + 12(1) - 0 = 6x^2 - 18x + 12\]

(b) At stationary points, \(\frac{\mathrm{d}y}{\mathrm{d}x} = 0\):
\[6x^2 - 18x + 12 = 0\]
\[6(x^2 - 3x + 2) = 0\]
\[6(x - 1)(x - 2) = 0 \implies x = 1 \text{ or } x = 2\]

When \(x = 1\):
\[y = 2(1)^3 - 9(1)^2 + 12(1) - 5 = 2 - 9 + 12 - 5 = 0\]
Stationary point is \((1, 0)\).

When \(x = 2\):
\[y = 2(2)^3 - 9(2)^2 + 12(2) - 5 = 16 - 36 + 24 - 5 = -1\]
Stationary point is \((2, -1)\).

To determine the nature, evaluate the second derivative \(\frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 12x - 18\):
- At \(x = 1\): \(\frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 12(1) - 18 = -6 < 0\), so \((1, 0)\) is a local maximum.
- At \(x = 2\): \(\frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 12(2) - 18 = 6 > 0\), so \((2, -1)\) is a local minimum.

Marking scheme

(a)
B2 for \(6x^2 - 18x + 12\) (B1 for two correct terms)

(b)
M1 for setting their derivative \(= 0\) and solving to find \(x = 1, 2\)
A1 for correct points \((1, 0)\) and \((2, -1)\)
B1 dep on M1 for correct determination of maximum and minimum with valid mathematical justification (e.g. correct second derivative test or evaluating gradient/values on either side)
Question 11 · structured
5 marks
The table shows information about the masses, \(m\) grams, of 120 apples picked from a tree.

\[\begin{array}{|c|c|} \hline \text{Mass } (m\text{ grams}) & \text{Frequency} \\ \hline 80 < m \le 110 & 18 \\ 110 < m \le 130 & 32 \\ 130 < m \le 150 & 44 \\ 150 < m \le 180 & 21 \\ 180 < m \le 200 & 5 \\ \hline \end{array}\]

(a) Calculate an estimate of the mean mass of an apple. [3]

(b) In a histogram representing this data, the height of the bar for the class interval \(110 < m \le 130\) is \(4.8\text{ cm}\).
Calculate the height of the bar for the class interval \(150 < m \le 180\). [2]
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Worked solution

(a) Find the midpoints \(x\) for each class interval:
- \(80 < m \le 110\): midpoint \(= 95\)
- \(110 < m \le 130\): midpoint \(= 120\)
- \(130 < m \le 150\): midpoint \(= 140\)
- \(150 < m \le 180\): midpoint \(= 165\)
- \(180 < m \le 200\): midpoint \(= 190\)

Calculate \(\sum fx\):
\[\sum fx = (18 \times 95) + (32 \times 120) + (44 \times 140) + (21 \times 165) + (5 \times 190)\]
\[\sum fx = 1710 + 3840 + 6160 + 3465 + 950 = 16125\]
\[\text{Estimated mean} = \frac{16125}{120} = 134.375\text{ g}\]
To 3 significant figures, mean \(= 134\text{ g}\).

(b) Frequency density for \(110 < m \le 130\):
\[\text{Class width} = 130 - 110 = 20\]
\[\text{Frequency density} = \frac{32}{20} = 1.6\]
Given bar height \(= 4.8\text{ cm}\), the scale factor is \(\frac{4.8}{1.6} = 3\text{ cm per unit of frequency density}\).

Frequency density for \(150 < m \le 180\):
\[\text{Class width} = 180 - 150 = 30\]
\[\text{Frequency density} = \frac{21}{30} = 0.7\]
\[\text{Height of bar} = 0.7 \times 3 = 2.1\text{ cm}\]

Marking scheme

(a)
M1 for using correct midpoints (at least 3 correct midpoints seen)
M1 (dep on previous M1) for \(\sum fx / 120\) using their midpoints
A1 for 134.375 or 134

(b)
M1 for frequency density \(21 / 30 = 0.7\) or scale relationship \(\frac{4.8}{(32/20)}\)
A1 for 2.1
Question 12 · structured
5 marks
A solid pyramid \(VABCD\) has a rectangular horizontal base \(ABCD\) where \(AB = 18\text{ cm}\) and \(BC = 14\text{ cm}\).
The vertex \(V\) is vertically above the centre \(M\) of the base \(ABCD\).
The vertical height \(VM = 22\text{ cm}\).

(a) Show that the length of the base diagonal \(AC = 22.8\text{ cm}\), correct to 1 decimal place. [2]

(b) Calculate the angle between the sloping edge \(VA\) and the base \(ABCD\). [3]
Show answer & marking scheme

Worked solution

(a) In the right-angled triangle \(ABC\):
\[AC^2 = AB^2 + BC^2\]
\[AC = \sqrt{18^2 + 14^2} = \sqrt{324 + 196} = \sqrt{520}\]
\[AC = 22.8035...\text{ cm}\]
Rounding to 1 decimal place gives \(AC = 22.8\text{ cm}\).

(b) \(M\) is the midpoint of diagonal \(AC\), so:
\[AM = \frac{1}{2} AC = \frac{\sqrt{520}}{2} = \sqrt{130} \approx 11.40175\text{ cm}\]
Triangle \(VMA\) is right-angled at \(M\). The angle between \(VA\) and the base is \(\angle VAM\):
\[\tan(\angle VAM) = \frac{VM}{AM} = \frac{22}{\sqrt{130}} = \frac{22}{11.40175...} \approx 1.92953...\]
\[\angle VAM = \tan^{-1}(1.92953...) \approx 62.602...^\circ\]
To 1 decimal place, the angle is \(62.6^\circ\).

Marking scheme

(a)
M1 for \(18^2 + 14^2\) or \(\sqrt{520}\)
A1 for \(22.803...\) shown to at least 4 significant figures before rounding to 22.8

(b)
M1 for identifying base length \(AM = 0.5 \times 22.803... = 11.40...\)
M1 for \(\tan(\theta) = \frac{22}{11.40...}\) or equivalent correct trig ratio
A1 for 62.6 or 62.60...
Question 13 · structured
5 marks
The functions \(\mathrm{f}\), \(\mathrm{g}\) and \(\mathrm{h}\) are defined by
\[\mathrm{f}(x) = 5 - 2x\]
\[\mathrm{g}(x) = \frac{3x + 4}{x - 2}, \quad x \ne 2\]
\[\mathrm{h}(x) = 2^x\]

(a) Find \(\mathrm{g}^{-1}(x)\). [3]

(b) Solve the equation \(\mathrm{f}(\mathrm{h}(x)) = -27\). [2]
Show answer & marking scheme

Worked solution

(a) Let \(y = \frac{3x + 4}{x - 2}\):
\[y(x - 2) = 3x + 4\]
\[yx - 2y = 3x + 4\]
\[yx - 3x = 2y + 4\]
\[x(y - 3) = 2y + 4\]
\[x = \frac{2y + 4}{y - 3}\]
Therefore,
\[\mathrm{g}^{-1}(x) = \frac{2x + 4}{x - 3}\]

(b)
\[\mathrm{f}(\mathrm{h}(x)) = \mathrm{f}(2^x) = 5 - 2(2^x)\]
Set equal to \(-27\):
\[5 - 2(2^x) = -27\]
\[-2(2^x) = -32\]
\[2^x = 16\]
Since \(16 = 2^4\):
\[x = 4\]

Marking scheme

(a)
M1 for multiplying by \((x - 2)\) to remove fraction: \(y(x - 2) = 3x + 4\)
M1 for isolating terms in \(x\): \(x(y - 3) = 2y + 4\) or \(y(x - 3) = 2x + 4\)
A1 for \(\frac{2x+4}{x-3}\) (or equivalent form \(\frac{-2x-4}{3-x}\))

(b)
M1 for setting \(5 - 2(2^x) = -27\) or \(2(2^x) = 32\) or \(2^{x+1} = 32\)
A1 for \(x = 4\)
Question 14 · structured
5 marks
The coordinates of two points are \(A(-3, 7)\) and \(B(5, 1)\).

(a) Find the gradient of the straight line \(AB\). [2]

(b) Find the equation of the perpendicular bisector of the line segment \(AB\).
Give your answer in the form \(y = mx + c\). [3]
Show answer & marking scheme

Worked solution

(a) Gradient of \(AB\):
\[m_{AB} = \frac{y_2 - y_1}{x_2 - x_1} = \frac{1 - 7}{5 - (-3)} = \frac{-6}{8} = -\frac{3}{4} = -0.75\]

(b) Midpoint \(M\) of \(AB\):
\[M = \left(\frac{-3 + 5}{2}, \frac{7 + 1}{2}\right) = \left(\frac{2}{2}, \frac{8}{2}\right) = (1, 4)\]

Gradient of the perpendicular line \(m_{\perp}\):
\[m_{\perp} = -\frac{1}{m_{AB}} = -\frac{1}{-\frac{3}{4}} = \frac{4}{3}\]

Using equation \(y - y_1 = m(x - x_1)\) with point \((1, 4)\):
\[y - 4 = \frac{4}{3}(x - 1)\]
\[y - 4 = \frac{4}{3}x - \frac{4}{3}\]
\[y = \frac{4}{3}x - \frac{4}{3} + \frac{12}{3}\]
\[y = \frac{4}{3}x + \frac{8}{3}\]

Marking scheme

(a)
M1 for \(\frac{1 - 7}{5 - (-3)}\) or \(\frac{7 - 1}{-3 - 5}\)
A1 for \(-\frac{3}{4}\) or \(-0.75\)

(b)
B1 for midpoint \((1, 4)\)
M1 for gradient \(m = -\frac{1}{\text{their } (a)} = \frac{4}{3}\)
A1 for \(y = \frac{4}{3}x + \frac{8}{3}\) (or \(y = 1.33x + 2.67\) with recurring decimals / equivalent fractional form)
Question 15 · structured
5 marks
In triangle \(OAB\), \(\vec{OA} = \mathbf{a}\) and \(\vec{OB} = \mathbf{b}\).
\(P\) is a point on \(AB\) such that \(AP : PB = 2 : 3\).
\(Q\) is a point on \(OB\) such that \(\vec{OQ} = \frac{2}{5}\mathbf{b}\).

(a) Write down \(\vec{AB}\) in terms of \(\mathbf{a}\) and \(\mathbf{b}\). [1]

(b) Find the position vector \(\vec{OP}\) in terms of \(\mathbf{a}\) and \(\mathbf{b}\). Give your answer in its simplest form. [2]

(c) Find \(\vec{QP}\) in terms of \(\mathbf{a}\) and \(\mathbf{b}\), and describe the geometric relationship between the line segments \(QP\) and \(OA\). [2]
Show answer & marking scheme

Worked solution

(a)
\[\vec{AB} = \vec{AO} + \vec{OB} = -\mathbf{a} + \mathbf{b} = \mathbf{b} - \mathbf{a}\]

(b) Since \(AP : PB = 2 : 3\), \(\vec{AP} = \frac{2}{5}\vec{AB}\):
\[\vec{OP} = \vec{OA} + \vec{AP} = \mathbf{a} + \frac{2}{5}(\mathbf{b} - \mathbf{a})\]
\[\vec{OP} = \mathbf{a} + \frac{2}{5}\mathbf{b} - \frac{2}{5}\mathbf{a} = \frac{3}{5}\mathbf{a} + \frac{2}{5}\mathbf{b}\]

(c)
\[\vec{QP} = \vec{QO} + \vec{OP} = -\vec{OQ} + \vec{OP}\]
\[\vec{QP} = -\frac{2}{5}\mathbf{b} + \left(\frac{3}{5}\mathbf{a} + \frac{2}{5}\mathbf{b}\right) = \frac{3}{5}\mathbf{a}\]
Geometric relationship: \(\vec{QP}\) is a scalar multiple of \(\vec{OA}\) (\(\vec{QP} = \frac{3}{5}\vec{OA}\)), which means \(QP\) is parallel to \(OA\) (and \(QP = \frac{3}{5} OA\)).

Marking scheme

(a)
B1 for \(\mathbf{b} - \mathbf{a}\)

(b)
M1 for \(\mathbf{a} + \frac{2}{5}(\mathbf{b} - \mathbf{a})\) or \(\mathbf{b} - \frac{3}{5}(\mathbf{b} - \mathbf{a})\)
A1 for \(\frac{3}{5}\mathbf{a} + \frac{2}{5}\mathbf{b}\)

(c)
B1 for \(\vec{QP} = \frac{3}{5}\mathbf{a}\)
B1 for stating that \(QP\) is parallel to \(OA\)
Question 16 · Extended Modelling & Calculus
6.5 marks
An open rectangular storage container has a horizontal square base of side length \(x\) metres and vertical height \(h\) metres.
The volume of the container is \(32\text{ m}^3\).

(a) Show that the external surface area of the open container, \(A\text{ m}^2\), is given by
\[ A = x^2 + \frac{128}{x} \]

(b) Find \(\frac{\mathrm{d}A}{\mathrm{d}x}\).

(c) Find the value of \(x\) for which the surface area is a minimum.

(d) Calculate the minimum external surface area of the container.
Show answer & marking scheme

Worked solution

(a) The volume of the container with a square base of side \(x\) and height \(h\) is:
\[ V = x^2 h = 32 \implies h = \frac{32}{x^2} \]
The container is open at the top, so it has 1 square base and 4 vertical rectangular faces:
\[ A = x^2 + 4(xh) = x^2 + 4x \left(\frac{32}{x^2}\right) = x^2 + \frac{128}{x} \]

(b) Differentiating \(A = x^2 + 128x^{-1}\) with respect to \(x\):
\[ \frac{\mathrm{d}A}{\mathrm{d}x} = 2x - 128x^{-2} = 2x - \frac{128}{x^2} \]

(c) For a stationary value (minimum surface area), set \(\frac{\mathrm{d}A}{\mathrm{d}x} = 0\):
\[ 2x - \frac{128}{x^2} = 0 \implies 2x = \frac{128}{x^2} \implies 2x^3 = 128 \implies x^3 = 64 \implies x = 4 \]

(d) Substituting \(x = 4\) into the area formula:
\[ A = 4^2 + \frac{128}{4} = 16 + 32 = 48\text{ m}^2 \]

Marking scheme

(a) M1 for expressing \(h\) in terms of \(x\) as \(h = \frac{32}{x^2}\) or \(x^2h = 32\)
A1 for complete unsimplified area expression \(x^2 + 4xh\) and substituting \(h\) to show \(A = x^2 + \frac{128}{x}\)

(b) B1 for \(2x\)
B1 for \(-128x^{-2}\) or \(-\frac{128}{x^2}\)

(c) M1 for setting their derivative \(\frac{\mathrm{d}A}{\mathrm{d}x} = 0\) and rearranging for \(x^3\)
A1 for \(x = 4\)

(d) B0.5 for \(48\) (or \(48\text{ m}^2\))
Question 17 · Solid Geometry & Mensuration
6.5 marks
A solid metal trophy is formed by joining a solid cone to a solid hemisphere of radius \(r\text{ cm}\).
The base of the cone is joined to the flat circular top of the hemisphere.
The vertical height of the cone is \(h\text{ cm}\) and its slant height is \(l\text{ cm}\).

(a) Given that the volume of the cone is equal to the volume of the hemisphere, show that \(h = 2r\).

(b) Given that \(r = 4.5\text{ cm}\),
(i) calculate the total volume of the trophy, giving your answer correct to 3 significant figures,
(ii) calculate the total surface area of the trophy, giving your answer correct to 3 significant figures.
Show answer & marking scheme

Worked solution

(a) Volume of the cone \(= \frac{1}{3}\pi r^2 h\).
Volume of the hemisphere \(= \frac{2}{3}\pi r^3\).
Setting them equal:
\[ \frac{1}{3}\pi r^2 h = \frac{2}{3}\pi r^3 \]
Dividing both sides by \(\frac{1}{3}\pi r^2\):
\[ h = 2r \]

(b)(i) When \(r = 4.5\text{ cm}\), \(h = 2(4.5) = 9\text{ cm}\).
Volume of the hemisphere \(= \frac{2}{3}\pi (4.5)^3 = 60.75\pi \approx 190.852\text{ cm}^3\).
Total volume \(= 2 \times 60.75\pi = 121.5\pi \approx 381.7035\text{ cm}^3\).
To 3 significant figures, \(\text{Volume} = 382\text{ cm}^3\).

(b)(ii) The slant height \(l\) of the cone is found using Pythagoras' theorem:
\[ l = \sqrt{r^2 + h^2} = \sqrt{4.5^2 + 9^2} = \sqrt{20.25 + 81} = \sqrt{101.25} \approx 10.0623\text{ cm} \]
The total external surface area consists of the curved surface area of the cone and the curved surface area of the hemisphere:
\[ \text{Curved surface of cone} = \pi r l = \pi \times 4.5 \times \sqrt{101.25} \approx 142.247\text{ cm}^2 \]
\[ \text{Curved surface of hemisphere} = 2\pi r^2 = 2\pi \times (4.5)^2 = 40.5\pi \approx 127.2345\text{ cm}^2 \]
\[ \text{Total surface area} = 142.247 + 127.2345 = 269.4815\text{ cm}^2 \]
To 3 significant figures, \(\text{Surface Area} = 270\text{ cm}^2\).

Marking scheme

(a) M1 for equating \(\frac{1}{3}\pi r^2 h = \frac{2}{3}\pi r^3\)
A1 for completing division clearly to arrive at \(h = 2r\)

(b)(i) M1 for \(\frac{4}{3}\pi (4.5)^3\) or \(\frac{1}{3}\pi(4.5)^2(9) + \frac{2}{3}\pi(4.5)^3\)
A1 for \(382\) or \(381.7\dots\)

(b)(ii) M1 for finding slant height \(l = \sqrt{4.5^2 + 9^2} = \sqrt{101.25}\) or \(10.06\dots\)
M1 for \(\pi \times 4.5 \times l + 2 \pi (4.5)^2\)
A0.5 for \(270\) or \(269.5\)
Question 18 · Functions & Composite / Inverse
6.5 marks
The functions \(f(x)\), \(g(x)\) and \(h(x)\) are defined by
\[ f(x) = 3x - 7 \]
\[ g(x) = \frac{6}{x + 1}, \quad x \ne -1 \]
\[ h(x) = 2^{x + 3} \]

(a) Find \(f^{-1}(x)\).

(b) Find \(gf(x)\). Give your answer as a simplified fraction.

(c) Find the value of \(x\) when \(h(x) = 128\).

(d) Solve the equation \(f(x) = g(x)\). Show all your working and give your solutions correct to 2 decimal places.
Show answer & marking scheme

Worked solution

(a) Let \(y = 3x - 7\).
\(y + 7 = 3x \implies x = \frac{y + 7}{3}\).
Therefore, \(f^{-1}(x) = \frac{x + 7}{3}\).

(b) \(gf(x) = g(f(x)) = g(3x - 7) = \frac{6}{(3x - 7) + 1} = \frac{6}{3x - 6}\).
Factorising the denominator: \(\frac{6}{3(x - 2)} = \frac{2}{x - 2}\).
Wait, check arithmetic: \(\frac{6}{3(x - 2)} = \frac{2}{x - 2}\).

(c) \(h(x) = 2^{x+3} = 128\).
Since \(128 = 2^7\):
\(x + 3 = 7 \implies x = 4\).

(d) \(f(x) = g(x) \implies 3x - 7 = \frac{6}{x + 1}\).
Multiplying by \((x + 1)\):
\((3x - 7)(x + 1) = 6\)
\(3x^2 + 3x - 7x - 7 = 6\)
\(3x^2 - 4x - 13 = 0\)
Applying the quadratic formula:
\[ x = \frac{-(-4) \pm \sqrt{(-4)^2 - 4(3)(-13)}}{2(3)} = \frac{4 \pm \sqrt{16 + 156}}{6} = \frac{4 \pm \sqrt{172}}{6} \]
\(\sqrt{172} \approx 13.11488\)
\[ x_1 = \frac{4 + 13.11488}{6} = \frac{17.11488}{6} \approx 2.8525 \to 2.85 \]
\[ x_2 = \frac{4 - 13.11488}{6} = \frac{-9.11488}{6} \approx -1.5191 \to -1.52 \]

Marking scheme

(a) B1 for \(\frac{x + 7}{3}\) or \(\frac{1}{3}(x + 7)\)

(b) M1 for \(\frac{6}{(3x-7)+1}\)
A1 for \(\frac{2}{x - 2}\) or \(\frac{6}{3x - 6}\)

(c) B1 for \(4\)

(d) M1 for forming quadratic \(3x^2 - 4x - 13 = 0\)
M1 for applying quadratic formula \(\frac{4 \pm \sqrt{(-4)^2 - 4(3)(-13)}}{2(3)}\)
A1.5 for \(x = 2.85\) and \(x = -1.52\) (awarded 0.75 for each correct value)
Question 19 · 3D Trigonometry & Solid Geometry
6.5 marks
The diagram shows a pyramid with a horizontal rectangular base \(ABCD\) and apex \(V\).
\(AB = 16\text{ cm}\) and \(BC = 12\text{ cm}\).
The apex \(V\) is vertically above the centre \(M\) of the base \(ABCD\).
The length of each sloping edge \(VA = VB = VC = VD = 26\text{ cm}\).

(a) Show that \(AC = 20\text{ cm}\).

(b) Calculate the vertical height \(VM\) of the pyramid.

(c) Calculate the angle between the sloping edge \(VA\) and the base \(ABCD\).

(d) Calculate the angle between the sloping face \(VBC\) and the base \(ABCD\).
Show answer & marking scheme

Worked solution

(a) Using Pythagoras' theorem on the right-angled triangle \(ABC\):
\[ AC = \sqrt{AB^2 + BC^2} = \sqrt{16^2 + 12^2} = \sqrt{256 + 144} = \sqrt{400} = 20\text{ cm} \]

(b) Since \(M\) is the centre of the rectangle, \(AM = \frac{1}{2} AC = \frac{20}{2} = 10\text{ cm}\).
In the right-angled triangle \(VMA\):
\[ VM = \sqrt{VA^2 - AM^2} = \sqrt{26^2 - 10^2} = \sqrt{676 - 100} = \sqrt{576} = 24\text{ cm} \]

(c) In right-angled triangle \(VMA\), the angle between edge \(VA\) and the base is \(\angle VAM\):
\[ \cos(\angle VAM) = \frac{AM}{VA} = \frac{10}{26} \]
\[ \angle VAM = \cos^{-1}\left(\frac{10}{26}\right) = \cos^{-1}(0.3846) \approx 67.380\dots^\circ \]
To 1 decimal place, the angle is \(67.4^\circ\).

(d) Let \(N\) be the midpoint of \(BC\). Then \(MN = \frac{1}{2} AB = \frac{16}{2} = 8\text{ cm}\).
The angle between the face \(VBC\) and the base \(ABCD\) is \(\angle VNM\):
\[ \tan(\angle VNM) = \frac{VM}{MN} = \frac{24}{8} = 3 \]
\[ \angle VNM = \tan^{-1}(3) \approx 71.565\dots^\circ \]
To 1 decimal place, the angle is \(71.6^\circ\).

Marking scheme

(a) B1 for \(\sqrt{16^2 + 12^2} = \sqrt{400} = 20\)

(b) M1 for \(AM = 10\) and \(VM = \sqrt{26^2 - 10^2}\)
A1 for \(24\)

(c) M1 for \(\cos(\angle VAM) = \frac{10}{26}\) or \(\sin(\angle VAM) = \frac{24}{26}\) or \(\tan(\angle VAM) = \frac{24}{10}\)
A1 for \(67.4^\circ\) or \(67.38\dots^\circ\)

(d) M1 for identifying \(MN = 8\) and using \(\tan(\theta) = \frac{24}{8}\)
A1.5 for \(71.6^\circ\) or \(71.56\dots^\circ\)
Question 20 · Calculus & Coordinate Geometry
6.5 marks
The equation of a curve is \(y = 2x^3 - 9x^2 + 12x + 1\).

(a) Find \(\frac{\mathrm{d}y}{\mathrm{d}x}\).

(b) Find the coordinates of the two stationary points on the curve.

(c) Determine the nature of each stationary point. Show how you decide.

(d) Find the equation of the tangent to the curve at the point where \(x = 3\). Give your answer in the form \(y = mx + c\).
Show answer & marking scheme

Worked solution

(a) Differentiating term by term:
\[ \frac{\mathrm{d}y}{\mathrm{d}x} = 6x^2 - 18x + 12 \]

(b) Stationary points occur when \(\frac{\mathrm{d}y}{\mathrm{d}x} = 0\):
\[ 6x^2 - 18x + 12 = 0 \implies x^2 - 3x + 2 = 0 \implies (x - 1)(x - 2) = 0 \]
So \(x = 1\) and \(x = 2\).
When \(x = 1\), \(y = 2(1)^3 - 9(1)^2 + 12(1) + 1 = 2 - 9 + 12 + 1 = 6\).
When \(x = 2\), \(y = 2(8) - 9(4) + 12(2) + 1 = 16 - 36 + 24 + 1 = 5\).
The coordinates are \((1, 6)\) and \((2, 5)\).

(c) Method 1: Second derivative
\[ \frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 12x - 18 \]
At \(x = 1\), \(\frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 12(1) - 18 = -6 < 0\), so \((1, 6)\) is a local maximum.
At \(x = 2\), \(\frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 12(2) - 18 = 6 > 0\), so \((2, 5)\) is a local minimum.

(d) At \(x = 3\):
\(y = 2(3)^3 - 9(3)^2 + 12(3) + 1 = 54 - 81 + 36 + 1 = 10\).
Gradient \(m = \frac{\mathrm{d}y}{\mathrm{d}x} = 6(3)^2 - 18(3) + 12 = 54 - 54 + 12 = 12\).
Equation of the tangent: \(y - 10 = 12(x - 3) \implies y = 12x - 36 + 10 \implies y = 12x - 26\).

Marking scheme

(a) B1 for \(6x^2 - 18x + 12\)

(b) M1 for solving their \(\frac{\mathrm{d}y}{\mathrm{d}x} = 0\)
A1 for both points \((1, 6)\) and \((2, 5)\)

(c) M1 for evaluating second derivative (or gradient test on either side) at \(x = 1\) and \(x = 2\)
A1 for correct deduction with working: \((1, 6)\) is a maximum and \((2, 5)\) is a minimum

(d) M1 for calculating \(y = 10\) and \(m = 12\) at \(x = 3\)
A0.5 for \(y = 12x - 26\)
Question 21 · Solid Geometry & Similarity
6.5 marks
A conical funnel has an open circular top of radius \(10\text{ cm}\) and vertical height \(24\text{ cm}\).

(a) Calculate the total capacity (volume) of the funnel in \(\text{cm}^3\).

(b) Water is poured into the funnel until the depth of the water is \(18\text{ cm}\).
(i) Find the radius of the circular surface of the water.
(ii) Calculate the volume of water in the funnel.

(c) The water drains out through a small hole at the vertex at a constant rate of \(15\text{ cm}^3/\text{s}\).
Calculate the time taken for all the water to drain out completely. Give your answer in seconds, correct to 1 decimal place.
Show answer & marking scheme

Worked solution

(a) The volume of the conical funnel is:
\[ V_1 = \frac{1}{3}\pi R^2 H = \frac{1}{3}\pi (10)^2 (24) = 800\pi \approx 2513.27\text{ cm}^3 \]
To 3 significant figures, \(V_1 = 2510\text{ cm}^3\).

(b)(i) The water forms a similar cone to the full funnel.
Using the scale factor of lengths:
\[ \frac{r}{10} = \frac{18}{24} \implies r = 10 \times \frac{3}{4} = 7.5\text{ cm} \]

(b)(ii) Volume of the water cone:
\[ V_2 = \frac{1}{3}\pi r^2 h = \frac{1}{3}\pi (7.5)^2 (18) = \frac{1}{3}\pi (56.25)(18) = 337.5\pi \approx 1060.2875\text{ cm}^3 \]
Alternatively, using the volume ratio:
\[ V_2 = \left(\frac{18}{24}\right)^3 \times 800\pi = \left(\frac{3}{4}\right)^3 \times 800\pi = \frac{27}{64} \times 800\pi = 337.5\pi \approx 1060\text{ cm}^3 \]
To 3 significant figures, \(V_2 = 1060\text{ cm}^3\).

(c) Time taken to drain:
\[ t = \frac{V_2}{\text{rate}} = \frac{337.5\pi}{15} = 22.5\pi \approx 70.6858\dots\text{ seconds} \]
To 1 decimal place, \(t = 70.7\text{ seconds}\).

Marking scheme

(a) M1 for \(\frac{1}{3}\pi (10)^2(24)\)
A1 for \(2510\) or \(2513\dots\) or \(800\pi\)

(b)(i) B1 for \(7.5\)

(b)(ii) M1 for \(\frac{1}{3}\pi(7.5)^2(18)\) or \(\left(\frac{18}{24}\right)^3 \times \text{their}(a)\)
A1 for \(1060\) or \(1060.28\dots\) or \(337.5\pi\)

(c) M1 for \(\frac{\text{their } 1060}{15}\)
A1.5 for \(70.7\) (accept \(70.68\dots\) to \(70.7\))

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