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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 21 Page 713

Use the formula for the surface area of a cone.

119π cm^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 We are told that the slant height of the cone equals 10cm. By substituting r=7 and l=10 into the formula, we can calculate the surface area of the cone.

S.A.=π rl+π r^2

r= 7, l= 10

S.A.=π( 7)( 10)+π( 7)^2

▼

Simplify right-hand side

Calculate power

S.A.=π(7)( 10)+49π

Multiply

S.A.=70π+49π

Add terms

S.A.=119π

The surface area of the cone is 119π square centimeters.

Subchapter links

Lesson Check p.712

Practice and Problem-Solving Exercises p.713-715

Standardized Test Prep p.715

Mixed Review p.715