Question

The top of a manhole cover is shaped like a circle. The area of the manhole cover is 380 square inches. What is the circumference of the manhole cover, to the nearest inch? 

Answer 1

need to find the radius first

 area = pi*r^2

380 = PI *r^2

380/PI = r^2

r^2 = 121

r = sqrt(121) = 11 inches

 radius is 11 inches

 now calculate circumference:

 c = 2*PI*r

 C = 2 * 3.14 * 11

circumference = 69.08 = 69 inches