Question

A circle has an area of 441π cm2. What is the circumference?

Answer 1

a = πr^2
441π = πr^2
441 = r^2
21 = r

C = 2rπ
= 2(21)π
= 42π cm^2 or 131.88 cm^2

Answer 2

A = πr^2
r^2 = 441π/π
r^2 = 441
r = 21

C = 2πr
C = 2π(21)
C = 42π

answer
42π cm