Proposition: Prop. 11.08: Line Parallel to Perpendicular Line to Plane is Perpendicular to Same Plane

Euclid's Formulation

If two straight lines are parallel, and one of them is at right angles to some plane, then the remaining (one) will also be at right angles to the same plane. * Let $AB$ and $CD$ be two parallel straight lines, and let one of them, $AB$, be at right angles to a reference plane. * I say that the remaining (one), $CD$, will also be at right angles to the same plane. fig08e

Modern Formulation

(not yet contributed)

Proofs: 1

Proofs: 1 2 3 4 5


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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