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McGraw Hill Integrated II, 2012

MH

McGraw Hill Integrated II, 2012 View details

2. Surface Areas of Prisms and Cylinders

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Exercise 46 Page 821

Use the formula for the surface area of a cylinder.

448 in^2

Practice makes perfect

Let's recall the formula for the surface area of a cylinder. S=2π rh+2π r^2Here, r is the radius of the base and h is the height of the cylinder. Let's start by finding the radius of the base. We can use the known formula for the circumference for the circle and substituting C with 16π.

C=2π r

C= 16π

16π=2π r

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Solve for r

.LHS /2π.=.RHS /2π.

8 = r

Rearrange equation

r = 8

Now we have enough information to find the surface area of the cylinder. Let's substitute r with 8 and h with 20 into the formula.

S=2π rh+2π r^2

r= 8, h= 20

S=2π( 8)( 20)+2π( 8)^2

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Simplify right-hand side

Calculate power

S=2π(8)(20)+2π(64)

Multiply

S=320π+128π

Add terms

S=448π

The surface area of the cylinder is about 448 in^2.

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Exercises p.817-821