CPCT stands for Corresponding Parts of Congruent Triangles.

It means that if any two triangles are congruent by ASA , SAS , RHS , SSS , then, their remaining sides and angles will also be equal.

Example:

If AB = YZ

BC = ZX

AC = YX

∴ Δ ABC Δ YZX ( SSS Congruence criterion )

⇒ angle A = angle Y , angle B = angle Z ,

angle C = angle X ( CPCT )

Hope this helps!!!!!