Triangles which are exactly the same shape **and **size are **congruent**.

NB. This also applies to shapes other than triangles.

Triangles are congruent for the following reasons:

**Three matching sides (SSS)**

**Two matching sides and the angle between them (SAS)**

**Two matching angles and a corresponding side (AAS)**

**In a right-angled triangle, the hypotenuse and one matching side (RHS)**