2.5 PROOFSSEGMENTS AND ANGLES

WHAT WE WILL LEARN

• Writing two column proofs• Name properties of congruence

NEEDED VOCAB

• Proof: logical argument that uses deductive reasoning to show that a statement is true• Two column proof: numbered statements and

corresponding reasons that show an argument in logical order• Theorem: statement that can be proven

EXS. 1, 3, AND 4 TWO COLUMN PROOFS

Statement

• 1. • 2. • 3. 2• 4. • 5.

Reason

• 1. Given• 2. Angle Add (Post 1.4)• 3. Substitution• 4. Angle Add (Post 1.4)• 5. Transitive prop.

MORE PRACTICE

Statement

• Do page 103 #13• 1. • 2. • 3. • 4. • 5.

Reason

• 1. Given• 2. Definition of linear pair• 3. Definition of supp • 4. Substitution Prop• 5. Definition of supp.

YOUR PRACTICE

Statement

• Do page 103 #14• 1.

• 3. • 4.

Reason

• 1. Given• 2. Def. of Bisector• 3. Transitive Prop• 4. Transitive Prop

EX. 2 NAMING PROPERTIES

• If and , then • Transitive prop

• If JLYZ, then YZJL• Symmetric prop