This page has been validated.
20
BOOK I. PROP. XX. THEOR.
NY two sides 
and 
of a triangle 
taken together are greater than the third side (
).
Produce , and make 
= (pr. 3.); draw 
.
Then because = (const.),
= 
(pr. 5.)
∴ 
> (ax. 9.)
∴ + > (pr. 19.)
and ∴ + > .
Q.E.D.
