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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 57 Page 838

Recall the formula for finding the area of a circle.

11.4cm

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 102cm^2. By substituting 102 for A in the formula, we can calculate r.

A=π r^2

A= 102

102=π r^2

▼

Solve for r

.LHS /π.=.RHS /π.

102/π = r^2

sqrt(LHS)=sqrt(RHS)

sqrt(102/π) = r

Rearrange equation

r = sqrt(102/π)

Use a calculator

r = 5.698035...

Round to 1 decimal place(s)

r≈ 5.7

We found that the radius is approximately 5.7cm. Now, to find the diameter, we can multiply the radius by 2. 2* 5.7=11.4cm

Subchapter links

Exercises p.834-838