# Circumference of a Circle

Written by Jerry Ratzlaff on . Posted in Plane Geometry

## Circumference of a Circle formulas

 $$\large{ C= 2 \; \pi \; r }$$ $$\large{ C= \pi \; d }$$ $$\large{ C = \sqrt{ 4 \; \pi \; A} }$$ $$\large{ C = 2 \; \sqrt{ \pi \; A} }$$ $$\large{ C = \frac{ 2 \; A }{ r } }$$

### Where:

$$\large{ C }$$ = circumference

$$\large{ A }$$ = area

$$\large{ d }$$ = diameter

$$\large{ r }$$ = radius