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Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
5. Finding Unknown Angle Measures
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Exercise 4 Page 391

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

Classification: Complementary angles.
Value of x: 31

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.
x^(∘)+ (2x-3)^(∘) = 90^(∘)
AddTerms

Add terms

3x^(∘) -3^(∘) = 90^(∘)
AddEqn

LHS+3^(∘)=RHS+3^(∘)

3x^(∘) = 93^(∘)
DivEqn

.LHS /3.=.RHS /3.

x^(∘) = 31^(∘)
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arrow_right Self-Assessment for Problem Solving p.393
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arrow_right Review & Refresh p.394
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