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Glencoe Math: Course 3, Volume 2

GM

Glencoe Math: Course 3, Volume 2 View details

5. Surface Area of Cones

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Exercise 6 Page 634

Use the formula for the surface area of a cone.

122.5 m^2

Practice makes perfect

The given solid is a cone.

To calculate the surface area of a cone, we can use the known formula where r is the radius of the base and l is the slant height of the cone. S=π rl+π r^2 Looking at the diagram, we know that the radius of the cone's base is 3 meters and that the the slant height of the cone equals 10 meters. By substituting r with 3 and l with 10 into the formula, we can calculate S.

S=π rl+π r^2

r= 3, l= 10

S=π( 3)( 10)+π( 3)^2

▼

Evaluate right-hand side

Calculate power

S=π(3)( 10)+π(9)

Multiply

S=30π+9π

Add terms

S=39π

Use a calculator

S=122.522113...

Round to 1 decimal place(s)

S≈ 122.5

The surface area of the cone is approximately 122.5 square meters.

Subchapter links

Guided Practice p.634

Independent Practice p.635-636

H.O.T. Problems p.636

Extra Practice p.637

Standardized Test Practice p.638

Common Core Review p.638