## Circle Geometry

The radius of a circle:

The radius of a circle is the distance from the center of the circle to the outside edge.

The diameter of a circle:

The diameter of a circle is longest distance across a circle. (The diameter cuts through the center of the circle. This is what makes it the longest distance.)

The circumference of a circle:

**The circumference of a circle is the perimeter -- the distance around the outer edge.**

**Circumference =**

where r = the radius of the circle

and pi = 3.141592...

where r = the radius of the circle

and pi = 3.141592...