2.6 prove statements about segments and angles
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2.6 Prove Statements About Segments and Angles. Objectives. Write proofs involving segment and angle addition Write proofs involving segment and angle congruence. Two-Column Proof. Recall what a two-column proof was… - PowerPoint PPT PresentationTRANSCRIPT
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2.6 Prove Statements About Segments and Angles
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Objectives
Write proofs involving segment and angle addition
Write proofs involving segment and angle congruence
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Two-Column Proof
Recall what a two-column proof was… Two-Column Proof – A proof format
used in geometry in which an argument is presented with two columns, statements and reasons, to prove conjectures and theorems are true. Also referred to as a formal proof.
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Statements ReasonsProof:
Two-Column Proof
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Given: PR = QS
Prove the following.
Prove: PQ = RS
1. GivenPR = QS1.
2. Subtraction PropertyPR – QR = QS – QR2.
3. Segment Addition Postulate
PR – QR = PQ; QS – QR = RS
3.
4. SubstitutionPQ = RS4.
Proof:Statements Reasons
Example 1:
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Prove the following.
Prove:
Given:
Your Turn:
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Proof:
Statements Reasons
1. Given
2. Transitive Property
3. Given
4. Addition Property
AC = AB, AB = BX
AC = BX
CY = XD
AC + CY = BX + XD
5. Segment Addition Property
AC + CY = AY; BX + XD = BDAY = BD 6. Substitution
1.
2.
3.
4.
5.
6.
Your Turn:
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Congruence of Segments
Theorem 2.1 (Congruence of Segments)Congruence of segments is reflexive, symmetric, and transitive.
Reflexive Property: AB ABSymmetric Property: If AB CD, then CD AB.Transitive Property: If AB CD and CD EF, then AB EF.
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Congruence of Angles
Theorem 2.2 (Congruence of Angles)Congruence of angles is reflexive, symmetric, and transitive.
Reflexive Property: A A Symmetric Property: If A B , then B A Transitive Property: If A B and B C , then A C .
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Prove the following.
Prove:
Given:
Example 2:
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1. Given1.
2. Definition of congruent segments2.
3. Given3.
4. Transitive Property4.
5. Transitive Property5.
Proof:
Statements Reasons
Example 2:
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Prove the following.
Prove:
Given:
Your Turn:
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Proof:
Statements Reasons
1. Given
2. Transitive Property
3. Given
4. Transitive Property
5. Symmetric Property
1.
2.
3.
4.
5.
Your Turn:
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Assignment
Geometry: Pg. 116 – 119
#3 – 13, 16, 21, 22