Step-by-step explanation:
Perimeter of semicircle
= Diameter + Arc of semicircle
= 2x + 0.5(π2x)
= πx + 2x. (C)
When πx + 2x = 25.71 cm,
we have x(π + 2) = 25.71cm.
=> x = 25.71 / (3.142 + 2) = 5.
Hence the radius x is 5cm.
