The Compendium Geometry is an eBook providing facts, formulas and explanations about geometry.

## Prism

In general, a prism is a polyhedron having two congruent polygonal faces and all other faces being parallelograms. A right prism is a prism where the vertical polygons are not parallelograms but rectangles (the simplest right prism is shown at the left). Prisms that are not right prisms are known as oblique prisms. A special case of a right prism is the cuboid, where both the top and the bottom faces are rectangles.

The volume of a right prism is given by the product of the base area Ab times the height h:

V = Abh.

The surface of a prism is given by the product of the circumference of the base face times the height h plus twice the area of the base face.

Regular Right Prisms

Regular right prism have a regular polygon of n vertices as top and bottom faces.

The relationship between the radius of the polygon r and its side a is determined by the following equation:

The surface of a regular n-prism can be calculated as follows:

The volume of regular n-prisms is given by

Last Update: 2011-01-11