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)
Mentioned in:
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)
 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