Proposition: 4.10: Construction of Isosceles Triangle whose Base Angle is Twice Apex
Euclid's Formulation
To construct an isosceles triangle having each of the angles at the base double the remaining (angle).
Modern Formulation
It is possible to construct an isosceles triangle having the angles at the base twice as big as the remaining angle (i.e. a triangle with the angles $72^\circ$, $72^\circ$ and $36^\circ$).
Table of Contents
Proofs: 1
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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