Circumference to Area

Question

Hello,

My question is how to convert circumference to area. For example, the circumference is 31.4 cm. Please explain in a simple way. Thank you for your help

Answer 1

C = circumference = 2πr

A = area = πr² = (πr)(r) = (C/2)(C/(2π))

So, A = C² / (4π)

If C = 31.4, then A = (31.4)² / (4π) = 78.46