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Big Ideas Math: Modeling Real Life, Grade 8

BI

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

2. The Pythagorean Theorem

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Exercise 10 Page 386

Use the Pythagorean Theorem.

12millimeters

Practice makes perfect

To find the missing side length of the triangle, we will use the Pythagorean Theorem. a^2+b^2=c^2

In the formula, a and b are the legs, and c is the hypotenuse of a right triangle. We are given a triangle with a=9millimeters and c=15millimeters.

Let's substitute these values into the formula.

a^2+b^2=c^2

a= 9, c= 15

9^2+b^2= 15^2

▼

Solve for b

Calculate power

81+b^2=225

LHS-81=RHS-81

81+b^2-81=225-81

Subtract terms

b^2=144

sqrt(LHS)=sqrt(RHS)

b=sqrt(144)

Calculate root

b=12

Since a negative side length does not make sense, we only need to consider positive solutions.

Subchapter links

Try It p.382-384

Self-Assessment for Concepts & Skills p.384

Self-Assessment for Problem Solving p.385

Review & Refresh p.386

Concepts, Skills, & Problem Solving p.386-388