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BOOK I. PROP. XXVI THEOR.
F two triangles have two angles of the one respectively equal to two angles of the other, (
= and 
= 
) and a side of the one equal to side of the other similarly placed with respect to the equal angles, the remaining sides and angles are respectively equal to one another.
Case I.
Case II.
CASE I.
Let 
and which lie between the equal angles be equal,
then 
= 
.
For if it be possible, let one of them be greater than the other;
make = , draw 
.
In 
and 
we have
= , = , = ;
∴ = 
(pr. 4.)
