Theorem 2-1 to 2-8

Theorem 2-6/T2-6

If the exterior sides of two adjacent acute angles are perpendicular, then the angles are complementary

Theorem 2-8/T2-8

If two angles are complements of congruent angles (or the same angle), then the two angles are congruent

Theorem 2-7/T2-7

If two angles are supplements of congruent angles (or the same angle), then the two angles are congruent

Theorem 2-4/T2-4

If two lines are perpendicular, then they form congruent adjacent angles

Theorem 2-5/T2-5

If two lines form congruent adjacent angles, then the lines are perpendicular

Theorem 2-1/T2-1

Midpoint Theorem: if M is the midpoint of AB, then AM=1/2AB and MB=1/2AB

Theorem 2-2/T2-2

Angle Bisector Theorem: If BX is the bisector of <ABC, then m<ABX=1/2m<ABC and m<XBC=1/2m<ABC

Theorem 2-3/T2-3

Vertical angles are congruent