Question

What is the use of CPCT

Answer 1

CPCT is the short form of corresponding part of congruent triangle , it is used when you have proved a triangle congruent using any of the congruence rule like SAS , ASA ,SSS etc and you you have to prove something else also which  doesn't come under that criteria ,as the  triangles are already congruent (which you have proved) their corresponding part will be also congruent hence we use cpct there.

Answer 2

Answer:

CPCT stands for corresponding parts of congruent triangles.

This is used when you have already proved that the triangles are congruent and you have to prove parts of the triangle which are not in the criteria and are corresponding to the vertex/ triangle.

Since triangles are congruent hence, both sides originating from equal angles in triangles can be proved equal through cpct.