Below, we have two triangles. All we know here is [b]2 angles and a non-included side of one triangle[/b] are congruent to[b] 2 angles and a non-included side of the other triangle[/b].
Are the triangles above congruent?
If you answered YES to the question above, which rigid transformations did you use to superimpose one triangle on top of the other?
The [b]Angle-Angle-Side Triangle Congruence Theorem[/b] should be no surprise to us. Which other triangle congruence theorem is disguised here?
If 2 angles of one triangle are congruent to 2 angles of another triangle, what can we conclude about the 3rd pair of angles?
Why can we make this conclusion?