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Corollary: Angles of Right Triangle

(related to Proposition: 1.32: Sum Of Angles in a Triangle and Exterior Angle)

If one angle of a triangle equals the sum of the other two, then it is a right angle. In other words, if \(\beta=\alpha + \gamma\) then \(\beta=90^\circ\).

triangle1

Table of Contents

Proofs: 1

Thank you to the contributors under CC BY-SA 4.0!

Github:
bookofproofs
non-Github:
@Calahan
@Casey

References

Adapted from CC BY-SA 3.0 Sources:

  1. Callahan, Daniel: "Euclid’s 'Elements' Redux" 2014

Adapted from (Public Domain)

  1. Casey, John: "The First Six Books of the Elements of Euclid"