In geometry, circumference is the distance around a closed curve; for example, a circle. It is a special kind of perimeter. The length of the circumference of a circle is often written as ${\displaystyle C}$,^[1] with:^[2][3]

${\displaystyle C=\pi d}$

where d is the diameter of the circle.

• Radius
• Pi

1. ↑ "List of Geometry and Trigonometry Symbols". Math Vault. 2020-04-17. Retrieved 2020-09-24.
2. ↑ Weisstein, Eric W. "Circle". mathworld.wolfram.com. Retrieved 2020-09-24.
3. ↑ "Radius, diameter, & circumference | Circles (article)". Khan Academy. Retrieved 2020-09-24.

The Simple English Wiktionary has a definition for: circumference.

• Numericana - Circumference of an ellipse
• Circumference of a circle With interactive applet and animation

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