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Big Ideas Math: Modeling Real Life, Grade 8

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Big Ideas Math: Modeling Real Life, Grade 8 View details

2. Solving Systems of Linear Equations by Substitution

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Exercise 23 Page 210

Recall the property about the measures of the interior angles in a triangle to create a system of linear equations. Then, use the Substitution Method to solve it.

System of Equations: ${y = 2.5 x 2 x + y = 180 (I) (II)$
Measures: Obtuse angle: $10 0^{\circ},$ acute angles: $4 0^{\circ}$

Practice makes perfect

We want to find the measures of the angles in a isosceles triangle by creating a system of linear equations and solving it. Let's take a look at the given diagram.

From the exercise, we know that the measure of the obtuse angle

y

is two and a half times the measure of one of the acute angles

x .

We can use this information to create the first equation.

y = 2.5 x

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Subchapter links

Try It p.206-207

Self-Assessment for Concepts & Skills p.207

Self-Assessment for Problem Solving p.208

Review & Refresh p.209

Concepts, Skills, & Problem Solving p.209-210