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Big Ideas Math: Modeling Real Life, Grade 8

BI

Big Ideas Math: Modeling Real Life, Grade 8 View details

Chapter Review

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Exercise 1 Page 131

Use the relationship of angles between parallel lines.

140^(∘), see solution.

Practice makes perfect

Let's consider the given diagram.

angles

To find the measure of ∠ 8, let's recall a definition of alternate exterior angles.

Alternate Exterior Angles
They are formed on the outside of the parallel lines and lie on opposite sides of the transversal.

Also, when a transversal intersects parallel lines, alternate exterior angles are congruent. Lines a and b are parallel and the given angle and ∠ 8 are alternate exterior angles. This means that these angles are congruent.

angles

Congruent angles have the same measure, so the measure of ∠ 8 is 140^(∘).

Subchapter links

1 Parallel Lines and Transversals p.131

2 Angles of Triangles p.132

3 Angles of Polygons p.132-133

4 Using Similar Triangles p.133