Glencoe Math: Course 3, Volume 2
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Glencoe Math: Course 3, Volume 2 View details
5. Surface Area of Cones
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Exercise 6 Page 634

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=Ï€ rl+Ï€ 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=Ï€ rl+Ï€ r^2
S=Ï€( 3)( 10)+Ï€( 3)^2
â–¼
Evaluate right-hand side
S=Ï€(3)( 10)+Ï€(9)
S=30Ï€+9Ï€
S=39Ï€
S=122.522113...
S≈ 122.5

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