In
geometry, a
circumscribed sphere of a
polyhedron is a
sphere that contains the polyhedron and touches each of the polyhedron's vertices. The word
circumsphere is sometimes used to mean the same thing. As in the case of two-dimensional
circumscribed circles, the radius of a sphere circumscribed around a polyhedron
P is called the
circumradius of
P, and the center point of this sphere is called the
circumcenter of
P.