User blog comment:HumpbackII/How to prove two triangles are congruent./@comment-24843074-20160423004648/@comment-24843074-20160423012634

Well the side lengths appear to be the 12m line and the 15m line. The angle that is shared between these two triangles are 30 degrees. Now SAS congruence has an included angle. This is shown in the first triangle.

However, in the second triangle, the angle shifts, and is no longer the included angle, which is needed for SAS. In the second triangle, it would be SSA, or @$$ (you know the letters), which is incorrect.