6–1 Line and Angle Relationships - Weeblycoyour.weebly.com/uploads/1/3/1/7/13179464/noteables_6-1.pdf · 6–1 Line and Angle Relationships ... relationships among different lines
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BRIDGES The sketch below shows a simple bridge design. The top beam and the fl oor of the bridge are parallel. If ∠2 � ∠3 and m∠3 = 55°, classify the relationship between ∠1 and ∠5. Then fi nd m∠1 and m∠5.
Since ∠3 and ∠5 are angles, they are
congruent. Also, since ∠1 and ∠2 are ,
∠1 and ∠3 are , and ∠1 and ∠5 are
supplementary.
Since m∠3 = 55° and ∠2 � ∠3, m∠2 = .
Since ∠3 and ∠5 are alternate interior angles, m∠5 = .
Since ∠1 and ∠2 are supplementary, the sum of their measures is 180°.
Therefore, m∠1 = 180° − 55° or .
Check Your Progress BRIDGES The sketch below shows a simple bridge design. The top beam and fl oor of the bridge are parallel. If m∠1 = 45° and m∠3 = 40°, fi nd m∠4.
1 4 2
3
ORGANIZE ITUse sketches and words to defi ne the lines and angles discussed in this lesson. Try to show relationships among different lines and angles. Write this in your Foldable.
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