Euclid:Proposition/VI/17

From ProofWiki
Jump to navigation Jump to search

Proposition

In the words of Euclid:

If three straight lines be proportional, the rectangle contained by the extremes is equal to the square on the mean; and, if the rectangle contained by the extremes is equal to the square on the mean, the three straight lines will be proportional.

(The Elements: Book $\text{VI}$: Proposition $17$)


Sources