A semicircle refers to half of a circle, that is, a shape enclosed by an arc formed by the center of the circle and two points on the circle. It has one diameter and one semicircular edge. The area of a semicircle is equal to half of the area of a circle. The area formula of a semicircle is as follows:
The formula is S = πr²/2, where r is the radius and π is the pi. If the radius of a semicircle is 5 cm, its area is 1/2 × π × 5 × 5 = 39.27 square centimeters. Semicircles are common shapes in daily life; for example, the rainbow below is semicircular.
