Page:First six books of the elements of Euclid 1847 Byrne.djvu/55

Rh F from any point within a triangle  straight lines be drawn to the extremities of one side, these lines must be together less than the other two sides, but must contain a greater angle.



Produce ,

+ >  (pr. 20.), add to each, + >  +  (ax. 4.)

In the same manner it may be shown that + >  +, ∴

+ >  + ,

which was to be proved. Again >  (pr. 16.),

and also >   (pr. 16.),

∴ >.

Q.E.D.