McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
5. Angles and Parallel Lines
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Exercise 4 Page 311

What is the relationship between ∠4 and ∠6?

Angle: m∠ 6=101^(∘)
Theorem: Alternate Interior Angles Theorem

Practice makes perfect

It is given that m∠ 4=101^(∘). Using this information, we need to find the measure of angle ∠ 6. We will use the given diagram to identify these angles. We can name the lines n and m for the following explanations to be more clear to follow as we proceed.

As we analyze the diagram, we notice that ∠ 4 and ∠ 6 lie on opposite sides of the transversal t. Additionally, they are on the interior sides of the parallel lines n and m. These are called alternate interior angles, so to find the measure of ∠ 6, we can then use the Alternate Interior Angles Theorem. Let's recall the theorem.

Alternate Interior Angles Theorem

If two parallel lines are cut by a transversal, then each pair of alternate interior angles is congruent.

According to the theorem, angles ∠ 4 and ∠ 6 are congruent and have the same measures. Therefore, we can write that m∠ 6=101^(∘). m∠ 4 = 101^(∘) and m∠ 4 = m∠ 6 ⇓ m∠ 6 = 101^(∘)

Extra

Further Explanation

Notice that since ∠ 3 and ∠ 5 also lie on opposite sides of the transversal t and on the interior sides of the parallel lines n and m, these angles are the alternate interior angels as well.