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3.1 Parallel Lines and Transversals
Comp book 3.1 Parallel Lines and Transversals Essential Question: How do we use parallel lines and transversals to identify angle measures? Take out 4 different colored pencils from blue box…or your own
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Complementary Angles = When sum of two angles equals 90°
Comp book Complementary Angles = When sum of two angles equals 90° O R N E
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Supplementary Angles = Straight When sum of two angles equals 180°
Comp book Supplementary Angles = Straight When sum of two angles equals 180°
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Vocabulary P || Q L ⊥ M Comp book
Parallel Lines – Lines in the same plane that do not intersect Perpendicular Lines – Intersecting lines whose angle measures 90° P || Q The symbol || means “is parallel to.” L ⊥ M The symbol ⊥ means “is perpendicular to.”
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Comp book Transversal: a line that intersects two or more lines. Transversals to parallel lines form special angle pairs. A ll B A B
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Adjacent angles: (next door & supplementary = 180)
Foldable Adjacent angles: (next door & supplementary = 180) 1 & 2 2 & 3 3 & 4 4 & 1 5 & 6 5 & 8 6 & 7 New diagram: color 7 & 8
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Vertical angles: (opposite & congruent)
Foldable 1 3 2 4 5 7 6 8 New diagram: color
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Corresponding angles:
f d Corresponding angles: a b c
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Foldable
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If parallel lines are crossed by a transversal then corresponding angles are congruent
*because lines are parallel* Not Corresponding: because lines are not parallel* 5 2 3 8 7 4 1 6 4 3 2 1 6 5 8 7
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Foldable Interior angles:
New diagram: Discuss the meaning of interior: color angles
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Foldable
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Foldable Exterior angles: New diagram: color exterior angles
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Foldable
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Foldable
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Foldable Adjacent Vertical
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Subtract known angle (100 degrees) from 180 degrees to find its supplementary adjacent angle
80
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80 and 100 form supplementary angle
80 100
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Vertical angles are congruent
80 100 80
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Corresponding angles from one of the parallel lines are all congruent to their corresponding angles on the second parallel line 80 100 100 80 100 80 80
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Find missing variable (x + 12)0 660
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Find missing variable 120 (x + 50)
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