WE know by given that <em>∠S ≅∠U</em> and<em> line ST ≅ line UT</em>
By the vertical angles theorem, we can find that ∠RTS ≅ ∠VTU.
They are in a form that when looking around the edge, you see congruent <em>angle, side, then angle</em>. That means that we can prove the triangles' congruence with ASA congruence.