### Exterior angle theorem

measure of the exterior angle is equal to the sum of the remote interior angles

### Third angles theorem

If two angles of one triangle are congruent to two angles of a second triangle, then the third angles are also congruent

### SSS Congruence postulate

if 3 sides of 1 triangle are are congruent to 3 sides of another triangle, then the 2 triangles are congruent

### SAS Congruence postulate

if 2 sides and the included angle of 1 triangle are congruent to 2 sides and the included angle of another triangle, then the 2 triangles are congruent

### ASA Congruence postulate

if 2 angles and the included side of one triangle are congruent to 2 angles and the included side of another triangle, then the 2 triangles are congruent

### AAS Congruence theorem

if two angles and a side of one triangle are congruent to the corresponding angles and side of another triangle, then they are congruent

### HL Congruence theorem

if in two right triangles, the hypotenuse and leg of one are congruent to the hypotenuse and leg of the other, then the triangles are congruent to each other