| A | B |
|---|
| Theorem 4-1 Congruent angles in ∆’ | If the two angles of one triangle are congruent to two angles of another triangle, then the third angles are congruent. |
| Postulate 4-1 Side-Side-Side (SSS) Postulate | If the three sides of one triangle are congruent to the three sides of another triangle, then the two triangles are congruent. |
| Postulate 4-2 Side-Angle-Side (SAS) Postulate | If two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the two triangles are congruent. |
| Postulate 4-3 Angle-Side-Angle (ASA) Postulate | If two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the two triangles are congruent. |
| Theorem 4-2 Angle-Angle-Side (AAS) Theorem | If two angles and a nonincluded side of one triangle are congruent to two angles and the corresponding nonincluded side of another triangle, then the triangles are congruent. |
| Theorem 4-3 Isosceles Triangle Theorem | If two sides of a triangle are congruent, then the angles opposite those sides are congruent. |
| Corollary to Isosceles Triangle Theorem | If a triangle is equilateral, then the triangle is equiangular. |
| Theorem 4-4 Converse of the Isosceles Triangle Theorem | If two angles of a triangle are congruent, then the sides opposite the angles are congruent. |
| Corollary to Converse of the Isosceles Triangle Theorem | If a triangle is equiangular, then the triangle is equilateral |
| Theorem 4-5 Vertex Angle of Isosceles ∆ | The bisector of the vertex angle of an isosceles triangle is the perpendicular bisector of the base. |
| Theorem 4-6 Hypotenuse-Leg (HL) Theorem | If the hypotenuse and a leg of one right triangle are congruent to the hypotenuse and a leg of another right triangle, then the triangles are congruent. |
