Question

Find the perimeter of the window to the nearest tenth.

A semi-circular windowpane with radius labeled 20 centimeters

Answer 1

102.8 cm

Explanation:

The perimeter of a semicircle is the sum of the length of the diameter and the length of the curved edge. The curved edge is half the circumference of a circle with the same radius.

perimeter = diameter + curved edge

= 2r +1/2(2πr) = r(2 +π)

= (20 cm)(2 +π) ≈ 102.8 cm

The perimeter of the window is about 102.8 cm.