Definition: Def. 11.03: Straight Line at Right Angles To a Plane

(Definition 3 from Book 11 of Euclid's “Elements”)

A straight line is at right angles to a plane when it makes right angles with all of the straight lines joined to it which are also in the plane.

Modern Formulation

(not yet contributed)

Proofs: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Propositions: 20 21 22 23 24


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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