SAS (Side-Angle-Side)

The SAS (Side-Angle-Side) theorem states that if two triangles have two sides and the included angle (the angle between those sides) equal to each other, then the triangles are congruent, meaning they have the same size and shape. Essentially, if you match two sides and the angle between them in one triangle to another, the triangles must be identical. This criterion helps establish triangle congruence by ensuring specific parts are equal, confirming the entire shape's equivalence without needing to compare all sides and angles.