McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
2. Surface Areas of Prisms and Cylinders
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Exercise 21 Page 818

Use the formula for the surface area of a cylinder.

Lateral Area: 155.8 in^2
Surface Area: 256.4 in^2

Practice makes perfect

We are asked to find the lateral area and surface area of the given cylinder.

We will do these things one at a time.

Lateral Area

Let's recall the formula for the lateral area L of a right cylinder. L=2π rh Here, r is the radius of the base, and h is the height of the cylinder. We will start by finding the radius of the base. In the diagram, we see that the base is a circle with diameter equal to 8in. Its radius is exactly the half of the length of the diameter. r = 8/2 ⇒ r = 4 We also see in the diagram that the height of the solid is 6.2in. With this information, we can find the lateral area of the prism.
L=2 π r h
L=2 π ( 4)( 6.2)
L=49.6 π
L=155.822995...
L≈ 155.8
The lateral area of the solid is 49.6 π in^2 that is approximately 155.8 in^2.

Surface Area

Let's recall the formula for the surface area of a cylinder. S=L+2π r^2 In this formula, r is the radius of the base and L is the lateral area of the cylinder. Substituting r with 4 and L with 49.6 π into the formula, we can calculate S. Let's do it!
S=L+2π r^2
S=49.6 π+2π( 4)^2
Simplify right-hand side
S=49.6 π+ 2π(16)
S=49.6 π+ 32π
S =81.6 π
S = 256.353960 ...
S≈ 256.4
The surface area of the cylinder is about 256.4 in^2.