Question

If r is the radius of a circle and d is its diameter, which of the following is an

equivalent formula for the circumference C = 2pie r​

Answer 1

C = 2πr is the same formula as C = πd since

two times the radius is equal to the diameter.

Check out the image below.

Answer 2

C = pi * d

Explanation:

C = 2 * pi *r

We want to replace with d

d = 2 * r

C = pi * 2r

C = pi * d