The equilateral angle corresponding to congruent triangles in Tang Dynasty (1) is the corresponding edge, and the edge between two corresponding angles is the corresponding edge.

(2) The angles of congruent triangles corresponding to equal sides are corresponding angles, and the angles between two corresponding sides are corresponding angles.

(3) If two congruent triangles have a common edge, then this common edge must be the corresponding edge.

(4) If two congruent triangles have a common angle, the common angle must be the corresponding angle.

(5) If two congruent triangles have antipodal angles, the antipodal angles must be corresponding angles.

(6) The longest side (or maximum angle) of two congruent triangles is the corresponding side (or corresponding angle), and the shortest side (or minimum angle) is the corresponding side (or corresponding angle).

As shown in the figure, complex geometric figures can often be regarded as a combination of simple figures. We should separate simple figures from complex figures, define corresponding concepts, deepen our understanding of concepts, and turn complex geometric problems into simple ones, which is the embodiment of the idea of reduction in mathematics.