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Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
3. Proofs with Parallel Lines
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Exercise 8 Page 142

Use the Converse of the Alternate Interior Angles Theorem.

x=20

Practice makes perfect

Both angles are in the interior of the diagram and on opposite sides of the transversal. Therefore, they are alternate interior angles.

According to the Converse of the Alternate Interior Angles Theorem, if the angles are congruent, then the lines are parallel. 2x+20=3x Let's solve this equation.
2 x + 20 = 3 x
SubEqn

LHS-2 x=RHS-2 x

20 = x
RearrangeEqn

Rearrange equation

x = 20
When x=20, the lines m and n are parallel.
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arrow_right Communicate Your Answer p.137
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arrow_right Monitoring Progress p.138-141
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arrow_right Exercises p.142-144
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Exercises 7 (Page 142)
Exercises 8 (Page 142)
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Exercises 10 (Page 142)
Exercises 11 (Page 142)
Exercises 12 (Page 142)
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Exercises 38 (Page 144)
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Exercises 40 (Page 144)
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Exercises 44 (Page 144)