Answer:
The ASA (Angle-Side-Angle) postulate
Explanation:
The ASA (Angle-Side-Angle) postulate states that if two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the two triangles are congruent.
Here, congruent angles are C and B with C' and B' and included side congruent is the side BC with the side B'C'
Hence,triangle ABC is congruent to triangle A'B'C' by the ASA postulate