I.26 Proposition I.26
If two triangles have the two angles equal to two angles respectively, and one side equal to one side, namely either the side adjoining the equal angles or that subtending one of the equal angles, they will also have the remaining sides equal to the remaining sides and the remaining angle equal to the remaining angle.
Proof
Apply I.4 to the congruent angle–side–angle case; for the AAS case
combine I.4 with I.16.
lines 74–74 in main.tex