In the given diagram, AB = DE, BC = DF. But the angles between AB and BC is not congruent to the angle between DE and DF.
Prove the following theorem:
If two triangles have a pair of unequal angles contained by two sides equal in pairs, and the third sides of the triangles are unequal, then the greater side is opposite the greater angle.

Move the vertices of the triagles and see how the measure of the AC and EF changes, depending the relation between the angles B and D