Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
Chapter Review
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Exercise 18 Page 753

50.3in.^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 From the diagram, we know that the diameter of the cone's base is 4inches. By dividing it by 2, we get the radius of the base. r=4in./2=2in. We are told that the slant height of the cone equals 6inches. By substituting r with 2 and l with 6 into the formula, we can calculate S.

S=Ï€ rl+Ï€ r^2
S=Ï€( 2)( 6)+Ï€( 2)^2
â–¼
Simplify right-hand side
S=Ï€(2)( 6)+Ï€(4)
S=12Ï€+4Ï€
S=16Ï€
S=50.26548...
S≈ 50.3

The surface area of the cone, to the nearest tenth, is 50.3in.^2.