Problem Solving (PS) | In the figure above, x =

If any two angles of any two triangles are congruent, the third angle is congruent, and the triangles are similar.

(The AA postulate comes from the fact that interior angles of a triangle always sum to 180. Two of three angles equal means both third angles are equal, too.)

Both triangles have a 90° angle, and congruent
...

---