Deductive Reasoning is a process of reasoning logically from given facts to a conclusion.

Addition Property of equality if a=b then a+c=b+c

Subtraction Property of equality if a=b then a-c=b-c

Multiplication Property of equalityif a = b then ac = bc

Division Property of equality if a=b then a/c = b/c c≠0

Substitution Property– if a=b, then b can replace a in any expression

Distributive Property – a(b+c) = ab + ac

Reflexive Property AB = AB Symmetric Property if AB = CD then CD

= AB Transitive Property if AB = CD & CD =

EF then AB = EF

Draw two intersecting lines. Fold the sides of <1 onto <2. What do

you notice? Fold the sides of <3 onto <4. what do

you notice? Make a conjecture about the angles

formed by two intersecting lines.

1

243

Vertical angles – two whose sides are opposite rays.

Adjacent angles – two coplanar angles with a common vertex, no common interior points.

Complementary angles – two angles , the sum of whose measure is 90.

Supplementary angles – two angles, the sum of whose measures is 180.

13

2

4

Vertical Angles Theorem – Vertical angles are congruent.

Congruent Supplements Theorem – If two angles are supplements of congruent angles (or of the same angle), then the two angles are congruent.

Congruent Complements Theorem – If two angles are complements of congruent angles (or of the same angle, then the two angles are congruent.