### Topic Page: Circumference

**circumference**from

*The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide*

In geometry, the curved line that encloses a curved plane figure, for example a circle or an ellipse. Its length varies according to the nature of the curve, and may be ascertained by the appropriate formula. The circumference of a circle is πd or 2πr, where d is the diameter of the circle, r is its radius, and π is the constant pi, approximately equal to 3.1416.

essays

Circles: working out area, diameter and radius

Beam me up, Scotty – Finding the Circumference of a Circle

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circle

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