# Circumference of a Circle

Written by Jerry Ratzlaff on . Posted in Plane Geometry

## Circumference of a Circle

### Circumference of a Circle formula

$$C= 2\pi r$$

$$C= \pi d$$

$$C = \sqrt { 4\pi A}$$

Where:

$$C$$ = circumference

$$r$$ = radius

$$d$$ = diameter

$$A$$ = area