1. Unique line postulate
Statement: Through any two points, there is exactly one line.
2. Line intersection postulate
Statement: If two lines intersect, then their intersection is exactly one point.
3. Segment addition postulate
Statement: If A, B and C are collinear and B is between A and C, then AB + BC = AC
4. Angle Addition postulate
Statement: If R is in interior of , then
.
5. Linear pair theorem
Statement: If two angles form a linear pair, then the angles are supplementary.
6. Congruent Complements theorem
Statement: If two angles are complementary to the same angle, then the angles are congruent.