Triangular Pyramid Frustum
The frustum of a triangular pyramid is equivalent to the sum of three pyramids whose common altitude is the altitude of the frustum and whose bases are the lower base, the upper base, and the mean proportional between the two bases of the frustum.
Keywordspyramid, pyramids, triangular, frustum, solids, mean proportional, equivalent, geometric solid, part of
G.A. Wentworth Plane And Solid Geometry (Boston: Ginn & Company, 1899) 318