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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

Mentioned in:

Proofs: 1
Sections: 2

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References

Adapted from (subject to copyright, with kind permission)

  1. Fitzpatrick, Richard: Euclid's "Elements of Geometry"

Adapted from CC BY-SA 3.0 Sources:

  1. Prime.mover and others: "Pr∞fWiki", https://proofwiki.org/wiki/Main_Page, 2016