Basic geometric figures (angles, sides, symmetry): แบบฝึกหัด

Which of the following geometric figures has exactly two lines of symmetry?

In an isosceles triangle \(ABC\), the vertex angle \(A\) is \(40^{\circ}\). If sides \(AB\) and \(AC\) are equal in length, find the size of the base angle \(B\).

A clock shows 08:45. What is the smaller angle formed between the hour hand and the minute hand?

In a triangle, the first angle is \(45^{\circ}\) and the second angle is \(75^{\circ}\). What is the size of the third angle?

A polygon has 5 sides of equal length. What is the name of this polygon? How many lines of symmetry does it have if it is a regular polygon?

In triangle \(PQR\), side \(PQ = PR\). If the vertex angle \(\angle QPR\) is \(40^{\circ}\), calculate the size of the base angle \(\angle PQR\).

In the figure, there is a quadrilateral \(ABCD\).
(a) If \(AB\) is parallel to \(DC\), and \(AD\) is parallel to \(BC\), and all four sides are equal in length, what is the name of this geometric figure?
(b) If the figure has exactly one pair of parallel sides (\(AD\) and \(BC\)) and the distance between these two sides is \(10\text{ cm}\), what type of quadrilateral is it?
(c) A shape has \(4\) equal sides and \(4\) right angles. How many lines of symmetry does this shape have?