Euclid:Proposition/I/15/Porism

Proposition

In the words of Euclid:

From this it is manifest that, if two straight lines cut one another, they will make the angles at the point of section equal to four right angles.

(The Elements: Book $\text{I}$: Proposition $15$ : Porism)

Sources

• 1926: Sir Thomas L. Heath: Euclid: The Thirteen Books of The Elements: Volume 1 (2nd ed.) ... (previous) ... (next): Book $\text{I}$. Propositions