**In this module, you can study ****how to calculate the distance around a circle (its circumference) if you know its diameter.**

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- Try your hand at changing a circumferenceDrag the radius of this circle to resize it and watch what happens to the circle's circumference (called perimeter in this example). If you have trouble with this virtual manipulative, try opening it in "full screen" mode.

The circumference of a circle is not equal to the length of two diameters.

A circle's circumference divided by its diameter is the same for every circle. (It's pi, or 3.14)

**Study and practice**

- Study how to find the circumference of a circleThis online lesson from onlinemathlearning.com provides a good explanation about how to use either radius or diameter to calculate the circumference of a circle. It includes a couple of embedded videos.
- Download a worksheet for area and circumference of a circleLink to math-aids.com to create your own worksheets for studying area and circumference of a circle. Answers included.
- Quiz yourself on finding circumferencesThis link from aaamath.com provides a circle's radius OR diameter and asks you to calculate the circumference.

Use these search terms to find additional resources:

*how to find circumferencecircumference measure*

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