Proposition: 6.24: Parallelograms About Diameter are Similar
(Proposition 24 from Book 6 of Euclid's “Elements”)
In any parallelogram the parallelograms about the diagonal are similar to the whole, and to one another.
Modern Formulation
If a parallelogram is divided into four parallelograms, then the two parallelograms lying on the diagonal are similar to each other and to the whole parallelogram.
Table of Contents
Proofs: 1
Mentioned in:
Proofs: 1 2
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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