Why is angle angle side called a theorem?

The Angle-Angle-Side (AAS) theorem is called a theorem because it is a proven statement in geometry that establishes a specific condition for triangle congruence. It states that if two angles and a non-included side of one triangle are congruent to two angles and the corresponding non-included side of another triangle, then the two triangles are congruent. The term "theorem" indicates that this result has been rigorously demonstrated through logical reasoning and proof within the framework of geometric principles.