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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

Practice Test

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Exercise 14 Page 402

Recall the formula for finding circumference of a circle given its diameter.

11.53cm

Consider a circle with the circumference of 36.2 centimeters.

We want to estimate the diameter of this circle given the circumference. The circumference C of a circle with diameter d is calculated using the formula below. C=π d We know that the circumference of the circle is 36.2cm. We can substitute 36.2 for C in the formula and then calculate d. We will use 3.14 as an estimate for π.

C=π d

C= 36.2, π= 3.14

36.2=( 3.14)(d)

Multiply

36.2=3.14d

.LHS /3.14.=.RHS /3.14.

36.2/3.14=d

Rearrange equation

d=36.2/3.14

Calculate quotient

d=11.528662 ...

Round to 2 decimal place(s)

d≈ 11.53

The diameter of the circle is approximately 11.53cm.

Extra

More About Circles!

Are you interested in learning more about circles? Our Mathleaks original content can teach you all about them! Check out the following resources to see real-world uses for circumference and area, how circles compare to other shapes and why, as well as some higher level topics that you can look forward to learning about in Geometry and Algebra 2.

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