What does cpctc represent and when would you use it

Corresponding parts of congruent triangles are congruent.

Step-by-step explanation:

This states that if the two sides/angles of a triangle are congruent,all other sides are also going to be congruent. It is a theorem for mainly trigonometry. According to the image attached any two congruent angles in any of the triangle will be congruent with the corresponding sides in the other triangle. It is used mainly in construction to re-enforce pillars and other structures.

angle POR=LMN if any of them is congruent according to the attached picture.

step-by-step explanation:

you can add the two numbers and divide the result by 2. or you can find the gap between the two numbers and add half of this to the smaller number.