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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 56 Page 838

Recall the formula for finding the area of a circle.

8.2m

Practice makes perfect

The area of a circle with radius r is calculated using the formula below. A=π r^2From the exercise, we know that the area of the circle is 54m^2. By substituting 54 for A in the formula, we can calculate r.

A=π r^2

A= 54

54=π r^2

▼

Solve for r

.LHS /π.=.RHS /π.

54/π = r^2

sqrt(LHS)=sqrt(RHS)

sqrt(54/π) = r

Rearrange equation

r = sqrt(54/π)

Use a calculator

r = 4.145929...

Round to 1 decimal place(s)

r≈ 4.1

We found that the radius is approximately 4.1m. Now, to find the diameter, we can multiply the radius by 2. 2* 4.1=8.2m

Subchapter links

Exercises p.834-838