Library/Geometry/Solid geometry/Prism/Sphere inscribed in a prism

Sphere inscribed in a prism

Overview
Important

A sphere is said to be inscribed in a prism if it fits perfectly inside the prism, touching all its faces but not crossing any. This means the sphere is tangent to every face of the prism.

Important properties

  • For a sphere to be inscribed, the prism must have enough symmetry (for example, a right prism with a regular polygon as its base).

  • The center of the inscribed sphere is equidistant from all the faces of the prism.

  • The radius of the inscribed sphere is equal to the shortest distance from the center to any face.

  • Not every prism can have an inscribed sphere; the base must allow a circle to be inscribed (i.e., the base must be tangential).