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Big Ideas Math: Modeling Real Life, Grade 7

BI

Big Ideas Math: Modeling Real Life, Grade 7 View details

5. Finding Unknown Angle Measures

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Exercise 26 Page 395

What is the sum of the measures of two complementary angles?

Classification: Complementary angles.
Value of x: 15

Practice makes perfect

First, let's take a look at the given diagram.

We have been given a pair of complementary angles and their measures written as algebraic expressions. Since the angles are complementary, we know that the sum of their measures should equal 90^(∘). We can solve for x by creating an equation using the expressions for the two smaller angles and their sum.

3x^(∘) + 45^(∘) = 90^(∘)

LHS-45^(∘)=RHS-45^(∘)

3x^(∘) = 45^(∘)

.LHS /3.=.RHS /3.

x^(∘) = 15^(∘)

Subchapter links

Try It p.390-392

Self-Assessment for Concept & Skills p.392

Self-Assessment for Problem Solving p.393

Review & Refresh p.394

Concept, Skills, & Problem Solving p.394-396