1. The problem statement, all variables and given/known data As given in the title. The law of cosines, the law of sines, or any other aspect of trigonometry may be used. Ultimately, I need to show that when two triangles have two pairs of proportional sides and the included angles congruent, that they are similar - that is, the remaining pair of sides are proportional and the other two angles are congruent. I could do it all if I could just prove that one of the other pairs of angles were congruent. 2. Relevant equations 3. The attempt at a solution I've spent 3+ hours now messing around with the law of sines, the law of cosines, and anything else I could think of. I honestly have no idea; nothing I've tried seems remotely close.