Similarity criteria are used to determine whether two figures are similar. There are three main criteria: Angle-Angle (AA), Side-Angle-Side (SAS), and Side-Side-Side (SSS).

• Angle-Angle (AA) Criteria: In this criterion, if two angles of one figure are equal to two angles of another figure, then the figures are considered similar. For example, if angle A and angle B of triangle ABC are equal to angle X and angle Y of triangle XYZ, then triangle ABC is similar to triangle XYZ.

• Side-Angle-Side (SAS) Criteria: According to this criterion, if two pairs of corresponding sides are proportional and the included angles are equal, the figures are similar. For instance, if side AB is proportional to side XY, side BC is proportional to side YZ, and angle B is equal to angle Y, then triangle ABC is similar to triangle XYZ.

• Side-Side-Side (SSS) Criteria: This criterion states that if the lengths of the corresponding sides of two figures are proportional, then the figures are similar. For example, if side AB is proportional to side XY, side BC is proportional to side YZ, and side AC is proportional to side XZ, then triangle ABC is similar to triangle XYZ.