# Circumference of a Circle

Submitted by Isoscel on Sat, 01/05/2008 - 06:27.

The circumference of a circle is pi times the diameter (the diameter is double the radius).

Let r be the radius of the circle and d be the diameter of the circle.

Then we have:

We can evaluate circle length using integral calculus.F0r

Circle length=

In this figure we have BC = d and AB = r.