7 terms

legs

two congruent sides of a triangle

vertex angle

angle formed by the two congruent sides.

base

side that is opposite to the vertex angle

base angles

angles that have base as an adjacent side.

AAS Congruence Criterion

If two angles and a non-included side of one triangle are congruent to the other angles and side respectively, then the triangles are congruent.

Isosceles Triangle Theorem

If the legs are congruent, then the triangle is an isosceles triangle (base angle are congruent).

Converse of the Isosceles Triangle Theorem

If the base angles are congruent, then the legs are congruent.