Big Ideas Math: Modeling Real Life, Grade 7
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5. Finding Unknown Angle Measures
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Exercise 1 Page 390

Adjacent angles share a common vertex and one side. The measures of complementary angles add up to 90^(∘). The measures of supplementary angles add up to 180^(∘). Vertical angles are opposite angles formed by an intersection of two lines.

Example Answer:
Adjacent Angles: ∠ LJKand∠ KJQ
Complementary Angles: ∠ MJN and ∠ NJP
Supplementary Angles: ∠ LJK and ∠ KJP
Vertical Angles: ∠ LJKand∠ PJN

Practice makes perfect

Before we take a look at the given diagram, let's start by defining adjacent, complementary, supplementary, and vertical angles.

Type of angle Description
Adjacent Two angles that share a common vertex and side.
Complementary Two angles whose measures have a sum of 90^(∘).
Supplementary Two angles whose measures have a sum of 180^(∘).
Vertical Opposite angles formed by an intersection of two lines.

Now, let's consider the given diagram.

To determine a pair of adjacent angles, let's take a look at the given diagram, looking for a pair of angles that share a vertex and a common side.

Looking at the diagram, ∠ LJK and ∠ KJQ share J as a vertex and JK as a side. Therefore, these angles are adjacent. Now, let's look for a pair of angles whose measures sum to 90^(∘) — a pair of complementary angles.

Looking at the markings on the given diagram, ∠ MJP is a right angle — its measure is 90^(∘). As ∠ MJN and ∠ NJP are adjacent angles that sum to ∠ MJP, they are complementary. Now, let's look for a pair of angles that sum to 180^(∘) — a pair of supplementary angles.

Looking at the markings on the given diagram, ∠ LJK and ∠ KJP sum to the straight angle ∠ LJP. Therefore, the sum of the measures of these angles is the measure of ∠ LJP — 180^(∘). As a result, ∠ LJK and ∠ KJP are supplementary. Finally, let's look for a pair of vertical angles. These angles are on the opposite sides of an intersection of two lines.

Looking at the diagram, ∠ LJK and ∠ PJN are on the opposite sides of an intersection of LP and NK. Therefore, these angles are vertical.