Proposition 7, Book XII, Euclid's Elements
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This Demonstration dynamically illustrates Proposition 7, Book XII of Euclid's Elements.
Contributed by: Izidor Hafner (May 2008)
Open content licensed under CC BY-NC-SA
Proposition 7, Book XII of Euclid's Elements states: Any prism which has a triangular base is divided into three pyramids equal to one another which have triangular bases . ("Equal" means "have the same volume".)  D. E. Joyce, "Euclid's Elements: Introduction."  Euclid, Elements, T. L. Heath, trans., as The Thirteen Books of Euclid’s Elements, 2nd ed., Book 3, New York: Dover Publications, 1956 p. 394.