Question

The area of a circle is 16π cm2. What is the circle's circumference?

Answer 1

Step 1, find it's radius.
Step 2, use that to find the circumference.

Answer 2

Area = pi*r^2
16 pi = pi r^2
16 = r^2
r = 4

Now,

C = 2 pi r
C = 2 pi (4)

Answer 3

The area of a circle is the formula is:
A = πr^2
C = 2πr
Just work backwards from the area formula and plug it into the circumference formula.