Proposition: Prop. 11.11: Construction of Straight Line Perpendicular to Plane from point not on Plane

Euclid's Formulation

To draw a perpendicular straight line from a given raised point to a given plane. * Let $A$ be the given raised point, and the given plane the reference (plane). * So, it is required to draw a perpendicular straight line from point $A$ to the reference plane. fig11e

Modern Formulation

(not yet contributed)

Proofs: 1

Proofs: 1 2 3 4

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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",, 2016