Big Ideas Math: Modeling Real Life, Grade 8
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Big Ideas Math: Modeling Real Life, Grade 8 View details
1. Parallel Lines and Transversals
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Exercise 9 Page 108

Use the relationship of angles between parallel lines.

Angle Measures: ∠3 = 95^(∘), ∠4=85^(∘)
Explanation: See solution.

Practice makes perfect

Let's consider the given diagram.

angles
To find the measure of ∠ 3, we will use the fact that corresponding angles of parallel lines are congruent. Since the 95^(∘) angle and ∠ 3 are corresponding angles and lines a and b are parallel, these angles are congruent.
angles

Congruent angles have the same measure, so the measure of ∠ 3 is 95^(∘). Finally, note that ∠ 4 and ∠ 3 form a straight line.

angles

Therefore, they are supplementary and the sum of their measures is 180^(∘). With this information, we can finally find the measure of ∠ 4. m∠ 4+ 95^(∘)=180^(∘) ⇕ m∠ 4=85^(∘)