Proposition: 6.31: Similar Figures on Sides of RightAngled Triangle
(Proposition 31 from Book 6 of Euclid's “Elements”)
In rightangled triangles, the figure (drawn) on the side subtending the right angle is equal to the (sum of the) similar, and similarly described, figures on the sides surrounding the right angle.
Modern Formulation
This is a generalization of the Pythagorean theorem, in which the squares are replaced by similar rectangles.
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