## Basic College Mathematics (9th Edition)

The distance around a circle is called the circumference. Therefore, the perimeter of a circle is known as the circumference. When finding the circumference of a circle there is only one unit involved. This leaves the units the same. Circumference: $C$ = $2$$\pi$$r$ Finding the circumference of a circle is like finding the perimeter of a triangle. If the circle's radius and diameter are measured in feet, then the unit for the circumference will be feet