This is a simple way to prove the congruence of triangles. SAS is an angular edge, the two sides of two triangles are equal, and the included angle is equal to prove congruence; ASA is an angle, the two angles of two triangles are equal, and the sides of the corresponding two corner clips are equal, which proves congruence; AAS is an angular edge, the corresponding angles of two triangles are equal, and the opposite sides of the two angles are equal, which can prove equality. I may not be able to explain clearly. You can look up "congruent triangles" in the encyclopedia.