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Pearson Geometry Common Core, 2011

PG

Pearson Geometry Common Core, 2011 View details

3. Surface Areas of Pyramids and Cones

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Exercise 20 Page 713

Use the formula for the surface area of a cone.

33π ft^2

Practice makes perfect

We want to find the surface area of the given cone.

To calculate the surface area of a cone, we can use the formula where r is the radius of the base and l is the slant height of the cone. S.A.=π rl+π r^2 From the diagram, we know that the diameter of the cone's base is 6ft. By dividing it by 2, we get the radius of the base. r=6/2=3ft We are told that the slant height of the cone equals 8ft. By substituting r=3 and l=8 into the formula, we can calculate the surface area of the cone.

S.A.=π rl+π r^2

r= 3, l= 8

S.A.=π( 3)( 8)+π( 3)^2

▼

Simplify right-hand side

Calculate power

S.A.=π(3)(8)+9π

Multiply

S.A.=24π+9π

Add terms

S.A.=33π

The surface area of the cone is 33π square feet.

Subchapter links

Lesson Check p.712

Practice and Problem-Solving Exercises p.713-715

Standardized Test Prep p.715

Mixed Review p.715