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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 9 Page 384

Use the Pythagorean Theorem.

3.2feet

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=2.4ft, c=4ft, and b=x.

Let's substitute these values into the formula.

a^2+b^2=c^2

SubstituteValues

Substitute values

2.4^2+ x^2= 4^2

▼

Solve for x

Calculate power

5.76+x^2=16

LHS-5.76=RHS-5.76

5.76+x^2-5.76=16-5.76

Subtract terms

x^2=10.24

sqrt(LHS)=sqrt(RHS)

x=sqrt(10.24)

Use a calculator

x=3.2

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