Chapter 4 Theorems, Postulates, and Definition

Isosceles Triangle Theorem : If two sides of a triangle are congruent, then the angles opposite those sides are congruent.

Converse of Isosceles Triangle Theorem : If two angles of a triangle are congruent, then the sides opposite those angles are congruent.

HL Theorem : If the hypotenuse and a leg of one right triangle are congruent to the hypotenuse and corresponding leg of another right triangle, then the triangles are congruent.

Third- Angle Theorem : If two angles of one triangle are congruent to two angles of a second triangle, then the third angles of the triangles are congruent.

LA Theorem : If one leg and an acute angle of one right triangle are congruent to the corresponding leg and acute angle of another right triangle, then the triangles are congruent.

HA Theorem : If the hypotenuse and acute angle of one right triangle are congruent to the hypotenuse and corresponding acute angle of another right triangle, then the two triangles are congruent.