Answer:
AA similarity theorem
Explanation:
You are given that two angles are congruent, so the appropriate choice is ...
AA similarity theorem
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Triangle similarity is shown by demonstrating that all three sides are proportional, or that two angles match (meaning the third one must also match). These methods would be abbreviated SSS (3 Sides) and AA (2 Angles), respectively. Since your problem statement involves angles and similarity, the choice is clear.