Sides can be shown to be congruent through tic marks. If two lines have the same number of tic marks then they are congruent. PQ and TU both have one, therefore they are congruent.
Angles are shown to be congruent through arcs. If two angles have the same numbers of arcs then they are congruent. <P and <Q both have two and <T and <U both have one. So they are congruent.
