Circumference - Geometry Made Easy
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Circumference of a Circle

Circumference of a circle

The circumference of a circle is the distance all the way around the circle. It's the same as the perimeter, but a special word that we only use for the perimeter of a circle. The circumference is always equal to twice the radius of the circle times π (pi), or 2πr.

Here's a proof that this is always true for any circle.

Learn by doing: figure out the circumference of a plate in your kitchen.
Area of a Circle
More about Geometry

Bibliography and further reading about circles:

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Copyright 2012-2015 Karen Carr, Portland State University. This page last updated September 2015.

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