## Prisms

A right **prism** is a polyhedron with the same polygon as its top and base, and rectangles as its remaining faces. The rectangular sides are perpendicular (at right angles) to the top and base, as shown in the diagram of the rectangular prism below. In this topic we will use prism when we mean right prism.

Cylinders are not prisms because they do not have rectangular side faces and a circle is not a polygon.

Every cross-section of a prism that is parallel to the base is the same as its top and base. Prisms are usually named according to the shape at the top and base.