radiusRadius2002-02-16 11:54:492002-02-16 13:58:22Definitioncirclesphereradius\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}
%\usepackage{psfrag}
%\usepackage{graphicx}
%\usepackage{xypic}The \emph{radius} of a circle or sphere is the distance from the center of the figure to the outer edge (or surface.)
This definition actually holds in $n$ dimensions; so 4th and 5th and $k$-dimensional ``spheres'' have radii. Since a circle is really a 2-dimensional sphere, its ``radius'' is merely an instance of the general definition.