• ### AA

A method for proving similarity of triangles: if two angles are congruent to their corresponding parts in another triangle, then the triangles are similar.

• ### AAS

A method for proving congruence of triangles: if two angles and a side not included by those angles are congruent to their corresponding parts in another triangle, then the triangles are congruent.

• ### ASA

A method for proving congruence of triangles: if two angles and their included side are congruent to their corresponding parts in another triangle, then the triangles are congruent.

• ### Congruent Triangles

Triangles whose corresponding angles and sides are all congruent.

• ### Congruent Polygons

Polygons whose corresponding sides and interior angles are all congruent.

• ### Corresponding Parts

The angles or sides in a polygon organized such that each angle and each side coincides with exactly one angle or side in another polygon--the pairs of angles and sides in each polygon are called corresponding parts.

• ### Hypotenuse-Leg

A method for proving congruence of right triangles: if one leg and the hypotenuse are congruent to their corresponding parts in another right triangle, the right triangles are congruent.

• ### SAS

A method for proving congruence or similarity of triangles: if two sides are congruent or proportional and their included angle is congruent to their corresponding parts of another triangle, then the triangles are congruent or similar, respectively.

• ### Similar Triangles

Triangles whose corresponding angles are congruent and whose corresponding sides are proportional. Congruence is a subset of similarity.

• ### SSS

A method for proving the congruence or similarity of triangles: if the three sides of a triangle are congruent to their corresponding parts, then the triangles are congruent. If the three sides of a triangle are proportional to their corresponding parts in another triangle, then the triangles are similar.