ASA (Angle-Side-Angle)

The ASA (Angle-Side-Angle) criterion is a method in geometry used to determine if two triangles are congruent, meaning they have exactly the same size and shape. If two triangles have one angle, the side between those angles, and a second angle, all equal respectively, then the triangles are congruent. This is because knowing these parts ensures all other sides and angles match, making the triangles identical in dimensions and form. ASA is a reliable way to prove triangle congruence when two angles and the included side are known.