Perimeter (pi, formula for circumference): แบบฝึกหัด

A circular tabletop has a diameter of \(21\text{ cm}\). Find the circumference of the tabletop. (Take \(\pi = \frac{22}{7}\))

A shape is formed by connecting a square and a semicircle. The side length of the square is \(14\text{ cm}\), and the diameter of the semicircle is equal to one side of the square. Find the perimeter of the entire shape. (Take \(\pi = \frac{22}{7}\))

A circular garden is surrounded by a path. The outer radius of the path is \(12\text{ m}\) and the inner radius is \(10\text{ m}\). If a gardener wants to place a fence along both the inner and outer boundaries of the path, what is the total length of the fence needed? (Take \(\pi = 3.14\))

A circle has a diameter of \(14\text{ cm}\). Find its circumference. (Take \(\pi = \frac{22}{7}\))

A bicycle wheel has a diameter of \(70\text{ cm}\). If the wheel completes \(50\) full rotations, how many metres does the bicycle travel? (Take \(\pi = \frac{22}{7}\))

A circular pond has a radius of \( 21 \text{ m} \). Find the circumference of the pond.
(Take \( \pi = \frac{22}{7} \))

A semicircle has a diameter of \( 28 \text{ cm} \). Find the perimeter of the semicircle. (Take \( \pi = \frac{22}{7} \))

A wire is bent to form a shape made of a semicircle and its diameter. If the circumference of the complete circle with the same radius is \(88\text{ cm}\), find the perimeter of this shape. (Take \(\pi = \frac{22}{7}\))

A circular pond has a circumference of \(44\text{ m}\).

(a) Find the radius of the pond.
(b) A stone path is built halfway around the pond along its edge. What is the length of this path?

(Take \(\pi = \frac{22}{7}\))

A piece of wire is used to form a shape consisting of a rectangle and a semicircle. The rectangle has a length of \(20\text{ cm}\) and a width of \(14\text{ cm}\). The semicircle is attached to one of the shorter sides of the rectangle, such that its diameter perfectly matches the width of the rectangle.

(a) Calculate the circumference of a full circle with the same diameter as the semicircle. (Take \(\pi = \frac{22}{7}\))
(b) Find the length of the curved part of the semicircle.
(c) Calculate the total perimeter of the entire shape.