Euclid:Proposition/III/19

Proposition

In the words of Euclid:

If a straight line touch a circle, and from the point of contact a straight line be drawn at right angles to the tangent, the centre will be on the straight line so drawn.

(The Elements: Book $\text{III}$: Proposition $19$)

Sources

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