SAS Similarity
Definition
AoPS
SAS stands for Side-Angle-Side, for two triangles to be similar triangles by SAS similarity, they must have a pair of congruent angles and the two sides next to the angle must be proportional.
Mathwords Definition
Side-angle-side similarity. When two triangles have corresponding angles that are congruent and corresponding sides with identical ratios as shown below, the triangles are similar.
Diagram
If and , then the triangles are similar by SAS similarity.