Conditional Statements

if then statements

Converse

when the hypothesis and the conclusion are reversed

Counterexample

a way to show that a mathematical statement is false

Biconditional

when a conditional AND its converse are both true they can be combined into a single statement with "if and only if"

Complementary angles

sum up to 90°

Supplementary angles

sum up to 180°

Vertical angles

two angles that are on opposite "sides" of two intersecting lines

Perpendicular lines

two lines that intersect to form right angles

theorem 2.2

Angle Bisector Theorem

theorem 2.3

Vertical angles are congruent

theorem 2.4

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

theorem 2.5

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

theorem 2.6

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

theorem 2.7

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

theorem 2.8

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