The normal elementary geometry : embracing a brief treatise on mensuration and trigonometry : designed for academies, seminaries, high schools, normal schools, and advanced classes in common schools (1884)
Brooks, Edward, 1831-1912 · Philadelphia : Christopher Sower Co. · leaf 139
there will re«main a pyramid whose base may be regarded as ACD,having its vertex at E. Now, the two pyramids ABC—Eand DEF—0 are equal in volume, since they have equalbases and equal altitudes (Th. XV.). Regarding the pyra-mid DEF—0 as having the base DCF and vertex &% E,it is equal in volume to… … BOOK VI. 135 three pyramids into which the prism is divided are allequal in volume. Therefore, etc. Cor. 1. A triangular pyramid is one-third of a prismhaving an equal base and an equal altitude. Cor. 2. The volume of a triangular pyramid is one-thirdof the product of its base and altitude. THEOREM…
Geometry · Plane trigonometry
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