2-3: Proving Theorems
Reasons used in Proofs
• Given information• Definitions• Postulates (Algebraic Properties included)• Theorems that have already been proved
• Theorem 2-1: The Midpoint Theorem– If M is the midpoint of AB, then AM = ½ AB and
MB = ½ AB
Let’s Look at Proof on page 43
• Theorem 2-2: The Angle Bisector Theorem– If ray BX is the bisector of <ABC , then m < ABX = ½
m <ABC and m <XBC = ½ m < ABCProve on your own
• Look at Example 2 on page 44
Classwork
• Pg 45: 1-10 together
Homework
• Pg 46: 1-8, 10-18, 19• study for quiz over 2.1-2.3
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