what is the vocabulary word?

Equilateral Triangle Isosceles Triangle Corresponding Angles
Vertex Angle Reflexive Property Alternate Interior Angles
Right Triangle Vertical Angles Base Angles
CPCTC

Once a triangle is proven congruent, then we can make the conclusion that all parts, including corresponding sides and angles, are congruent.

CPCTC (Corresponding Parts of Congruent Triangles are Congruent)