Question

difference between included angle and interior angle

Answer 1

n the context of congruency, an included angle is the angle between two given sides. An interior angle of a triangle may be any of the angles, not necessarily between the two sides being used to test for congruency. 

Triangles in which two sides and the included angle match (SAS triangles) are always congruent. Triangles with two matching sides and a matching angle that is not included (SSA triangles) may or may not be congruent, depending on the size of the angle.