+ DO NOW- Complete #1-5 on the proofs worksheet that you picked up from the back of the classroom.

+ Use the reasons below to complete the proofs for 4&5 Definition of Midpoint Given Substitution Definition of Congruence Segment Addition Transitive Property Subtraction Given Definition of Congruence Segment Addition Substitution Definition of Congruence Number 4Number 5

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+ Given AB = BC Prove AC=2BC StatementsReasons 1) AB=BC1) 2)2) Segment Addition 3) BC+BC=AC3) 4) 4) Simplify 5) AC=2BC5)

+ Given AB = BC Prove AC=2BC StatementsReasons 1) AB=BC1)Given 2) AB+BC=AC2) Segment Addition 3) BC+BC=AC3) Substitution BC for AB 4) 2BC=AC4) Simplify 5) AC=2BC5) Reflexive Property

+ Try on your own: Given JK = KL Prove JL=2JK JK L

+ 2.8 Proving Angle Relationships Example:

+ USING THE ANGLE ADDITION POSTULATE PRACTICE

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+ Given: Angle ABC is a right Angle Prove: Angle ABD and Angle DBC are complementary

+ Given: Angles 1 and 2 form a linear pair. M<1 + M<3 = 180 Prove StatementsReasons 1) Angles 1 & 2 are a LP1) 2) 2) Given 3) 3) The supplement theorem 4) Angles 1 and 34) are supplementary 5) 5) congruent supplements thm

+ Given: Angles 1 and 2 form a linear pair. M<1 + M<3 = 180 Prove StatementsReasons 1) Angles 1 and 2 are a LP1) Given 2) M<1 + M<3 = 180 2) Given 3) Angles 1 and 2 are3) Supplement Thm supplementary 4) Angles 1 and 34) Def of are supplementarysupplementary angles 5) 2 and 3 are congruent5) congruent supplements thm

+ You try: