# Radius

From Encyclopedia of Mathematics

*of a circle*

A segment joining a point of the circle (or sphere) to the centre. The length of this segment is also called the radius.

#### Comments

For the radius of curvature of curves, surfaces and higher-dimensional differential-geometric objects, cf. e.g. Curvature and Differential geometry.

#### References

[a1] | M. Berger, "Geometry" , I , Springer (1987) |

[a2] | H.S.M. Coxeter, "Introduction to geometry" , Wiley (1963) |

**How to Cite This Entry:**

Radius. BSE-3 (originator),

*Encyclopedia of Mathematics.*URL: http://encyclopediaofmath.org/index.php?title=Radius&oldid=12340

This text originally appeared in Encyclopedia of Mathematics - ISBN 1402006098