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Warm-upName the angle pair relationships.
123
4
56
78
1 and 6 - 2 and 7 - 3 and 5 -4 and 5 - 6 and 7 - 1 and 4 -
CorrespondingAlternate ExteriorAlternate InteriorConsecutive InteriorLinearVertical
Benchmark #12!!
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Geometry Notes3.1 - Properties of Parallel Lines
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Parallel Line Theorems
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Corresponding Angles Postulate
If two lines are parallel (and cut by a transversal), then the corresponding angles are congruent. (Postulate 3-1)
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Alternate Interior Angles Theorem
If two lines are parallel, then the alternate interior angles are congruent.
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Alternate Exterior Angles Theorem
If two lines are parallel, then the alternate exterior angles are congruent.
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Same-Side Interior Angles Theorem
If two lines are parallel, then the consecutive interior angles are supplementary.
Also works with Same-Side Exterior Angles
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So which is which?≅ (Congruent)
•corresponding•alternate
✤interior✤exterior
•vertical
adds to 180 (supplementary)
•same-side✤interior✤exterior
•linear
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ExamplesExample 1:
Find the missing angles.
x
y75°
x=75° because it is corresponding with 75°.
y=75° because it is alternate exterior
with x.
Example 2: Solve for x.
5x-24
89
89 + 5x-24 = 180°(Consecutive angles are
Supplementary)5x + 65 = 180
5x = 115x = 23°
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How to set it up:
Decide what kind of angle relationshipDecide ≅ or _ + _ = 180Set it and Solve itCheck it
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Assignments:
Angle Pairs Worksheet
#16 p. 131 #1-13 (odd), 14-17, 19-22
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