Question

What needs to happen before you can use the reason CPCTC?

Answer 1

Answer with explanation:

CPCTC=Corresponding parts of Congruent triangles

Before using the Reason , C P C TC, we Prove two triangles Congruent.

The two triangles can be proven congruent by four ways:

 1. →S S S

 2.→S AS

 3.→A S A

 4.→ A A S

⇒So, if triangles are proven congruent by, S S S, then by Reason  C P C T C, then other three corresponding angles we prove congruent.

⇒ If triangles are proven congruent by, S A S, then by Reason  C P C T C,other two corresponding angles and one side, we prove congruent.

⇒So, if triangles are proven congruent by, A S A, then by Reason  C P C T C, then one corresponding angle and other two corresponding sides , we prove congruent.

⇒So, if triangles are proven congruent by, A A S, then by Reason  C P C T C, one corresponding angle and other two corresponding sides ,we prove congruent.

Answer 2

Before you can use the reason CPCTC, you need to show that two figures which usually are triangles to be congruent. After showing such, you can then say Corresponding parts of the two congruent figures are also congruent to each other.