Similarity Criteria: AAA And AA

Consider $\triangle ABC$ and $\triangle PQR$. We are given the angle measures: $\angle A = 60^\circ$, $\angle B = 80^\circ$, and $\angle C = 40^\circ$ for the first triangle. For the second triangle, we have $\angle P = 60^\circ$, $\angle Q = 80^\circ$, and $\angle R = 40^\circ$. By comparing corresponding parts, we see that $\angle A = \angle P =$ $^\circ$. Similarly, $\angle B = \angle Q =$ $^\circ$, and $\angle C = \angle R = 40^\circ$. Therefore, we can conclude that $\triangle ABC \sim \triangle$ based on the similarity criterion.