View source for Radius

''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|Curvature]] and [[Differential geometry|Differential geometry]].

====References====
<table><TR><TD valign="top">[a1]</TD> <TD valign="top">  M. Berger,   "Geometry" , '''I''' , Springer  (1987)</TD></TR><TR><TD valign="top">[a2]</TD> <TD valign="top">  H.S.M. Coxeter,   "Introduction to geometry" , Wiley  (1963)</TD></TR></table>