2.1 Inductive Reasoning and ConjectureInductive Reasoning – Reasoning that uses a number of specific examples to arrive at a conclusion.Conjecture – A concluding statement reached using inductive reasoning.Counterexample – An example to show that a conjecture is not true.

2.2 LogicTruth Value – The truth or falsity of a statement.Negation – The opposite meaning of a statement.Compound Statement – Two or more statements joined by the word and or or.Conjunction – A compound statement using the word and.Disjunction – A compound statement using the word or.

Truth Table – A convenient method for organizing the truth values of statements.

2.3 Conditional StatementsConditional Statement – A statement that can be written in if-then form.

2.4 Deductive ReasoningDeductive Reasoning – An argument using facts, rules, definitions, or properties to reach a logical conclusion.

2.5 Postulates and Paragraph ProofsPostulate – A statement that is accepted as true without proof.

Also known as an axiom.

Proof – A logical argument in which each statement you make is supported by a statement that is accepted as true.Theorem – A statement or conjecture that has been proven.

Paragraph Proof – An informal proof that involves writing a paragraph to explain why a conjecture for a given situation is true.

2.6 Algebraic ProofAlgebraic Proof – A proof that is made up of a series of algebraic statements.

Two-Column Proof – A formal proof that contains statements and reasons organized in two columns.

Property Segments Angles

Reflexive AB = AB m<1=m<1

Symmetric If AB=CD,

then CD=AB.

If m<1=m<2 ,

thenm<2=m<1.

Transitive If AB=CD and CD=EF, then AB=EF.

If m<1=m<2

¿m<2=m=3 ,

thenm<1=m<3

2.7 Proving Segment Relationships

2.8 Proving Angle Relationships