The second criterion swaps the roles: instead of two sides and the included angle, one starts from one side and the two angles that rest on it.
Theorem — Second congruence criterion
If two triangles have respectively congruent one side and the two adjacent angles, then they are congruent.
This criterion is the one used most often when the given information concerns the angles rather than the sides.
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Topics: Euclidean geometry
Concepts: Angle · Congruence · Congruence criteria · Triangle
Skills: Synthetic geometry