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McGraw Hill Integrated II, 2012

MH

McGraw Hill Integrated II, 2012 View details

4. Volumes of Prisms and Cylinders

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Exercise 59 Page 838

Recall the formula for finding the area of a circle.

9.3in

Practice makes perfect

The area of a circle with radius r is calculated using the formula below. A=π r^2 From the exercise, we know that the area of the circle is 271in^2. By substituting 271 for A in the formula, we can calculate r.

A=π r^2

A= 271

271=π r^2

▼

Solve for r

.LHS /π.=.RHS /π.

271/π = r^2

sqrt(LHS)=sqrt(RHS)

sqrt(271/π) = r

Rearrange equation

r = sqrt(271/π)

Use a calculator

r = 9.287732...

Round to 1 decimal place(s)

r≈ 9.3

The radius is approximately 9.3in.

Subchapter links

Exercises p.834-838