
frustum of a pyramid


The portion remaining with the original base of a pyramid when the pyramid is cut through by a plane parallel to its base.
The original base and the section cut by the parallel plane are called the bases of the frustum. The other faces are called lateral faces of the frustum. These lateral faces are all trapezoids. The intersections of the adjacent lateral faces are called the lateral edges of the frustum. An altitude of the frustum is defined as a segment joining the two base planes and perpendicular to both. The length of an altitude is called the height of the frustum.

