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 140
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… … Draw the diagonals A C and AD, andpass the planes SA C and SAD throughthese diagonals and the vertex S; thepyramid will then be divided into tri-angular pyramids, whose altitiides areequal, being the altitude of the pyra-mid. Now, the volume of each ofthese triangular pyramids is equal toits base…
Geometry · Plane trigonometry
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