7th Grade Math

Surface Area of a Cylinder

Find the surface area of the cylinder.

7 m

2 m

Round to the nearest tenth.

S.A. = 2 πrh + 2 πr^2 Surface area of a cylinder

= 2 π(2)(7) + 2 π(2)^2 Replace r with 2 and h with 7.

≈ 113.1 Simplify.

The surface area is about 113.1 square meters.

a. Find the surface area of the cylinder.

Round to the nearest tenth.

9 ft

3 ft

CAROUSELS A circular fence that is 2 feet high is to be built around

the outside of a carousel. The distance from the center of the

carousel to the edge of the fence will be 35 feet. How much

fencing material is needed to make the fence around the carousel?

The radius of the circular fence is 35 feet. The height is 2 feet.

S.A. = 2 πrh Curved surface of a cylinder

= 2 π(35)(2) Replace r with 35 and h with 2.

≈ 439.8 Simplify.

So, about 439.8 square feet of material is needed to make the fence.

b. DESIGN Find the area of the label of a can of tuna with a radius

of 5.1 centimeters and a height of 2.9 centimeters. Round to the

nearest tenth.

Real-World Link

Of the 3,000 to 4,000

wooden carousels

carved in America

between 1885 and

1930, fewer than 150

operate today.

RRR

O

Example 1 Find the surface area of each cylinder. Round to the nearest tenth.

11

2 mm

5 mm 2.

8 in.

11 in.

Example 2 3. STORAGE The height of a water tank is 10 meters, and it has a diameter of

10 meters. What is the surface area of the tank? Round to the nearest tenth.

Lesson 2C Surface Area 589

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