Proposition: Prop. 12.05: Sizes of Tetrahedra of Same Height are as Bases
Euclid's Formulation
Pyramids which are of the same height, and have triangular bases, are to one another as their bases.
 Let there be pyramids of the same height whose bases (are) the triangles $ABC$ and $DEF$, and apexes the points $G$ and $H$ (respectively).
 I say that as base $ABC$ is to base $DEF$, so pyramid $ABCG$ (is) to pyramid $DEFH$.
Modern Formulation
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Table of Contents
Proofs: 1
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References
Adapted from (subject to copyright, with kind permission)
 Fitzpatrick, Richard: Euclid's "Elements of Geometry"
Adapted from CC BYSA 3.0 Sources:
 Prime.mover and others: "Pr∞fWiki", https://proofwiki.org/wiki/Main_Page, 2016