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Big Ideas Math: Modeling Real Life, Grade 8

BI

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

7. Perimeters and Areas of Similar Figures

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Exercise 12 Page 88

The ratio of the corresponding side lengths is equal to the ratio of the perimeters.

8.4

Practice makes perfect

We are given a pair of similar figures.

similar figures

The ratio of the perimeters is 7: 10. Knowing that the ratio of corresponding side lengths is the same as the ratio of the perimeters, we can write a proportion in terms of x. Be sure to keep the larger side length and the larger perimeter on the same side of the fraction bar. x/12=7/10 We can now isolate x in this equation and find its value.

x/12=7/10

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Solve for x

LHS * 12=RHS* 12

x=7/10(12)

MoveRightFacToNum

a/c* b = a* b/c

x=7(12)/10

Multiply

x=84/10

a/b=.a /2./.b /2.

x=42/5

Calculate quotient

x=8.4

Subchapter links

Try It p.84-85

Self-Assessment for Concepts & Skills p.85

Self-Assessment for Problem Solving p.86

Review & Refresh p.87

Concepts, Skills, & Problem Solving p.87-88