Radius

For other uses, see Radius (disambiguation).

In classical geometry, a radius of a circle or sphere is any line segment with one endpoint on the circle (i.e., the circular boundary) and the other at the center of the circle. By extension, the radius of a circle or sphere is the length of any such segment. The radius is half the length of the diameter.

• More generally — in geometry, engineering, graph theory, and many other contexts — the radius of something (e.g. a cylinder, a graph, or a mechanical part) is the distance from its center or axis to its outermost points. See also diameter.

See also

• bend radius