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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 23 Page 637

Use the formula for the surface area of a cone.

$188.5 yd^{2}$

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 r ℓ + π r^{2}

Looking at the diagram, we know that the radius of the cone's base is

3

yards and that the slant height of the cone equals

17

yards. By substituting

r

with

3

and

ℓ

with

17

into the formula, we can calculate

S .

S = π r ℓ + π r^{2}

$r = 3$ , $ℓ = 17$

S = π (3) (17) + π (3)^{2}

▼

Evaluate right-hand side

Calculate power

S = π (3) (17) + π (9)

Multiply

S = 51 π + 9 π

Add terms

S = 60 π

Use a calculator

S = 188.495559 \dots

Round to $1$ decimal place(s)

S \approx 188.5

The surface area of the cone is approximately

188.5

square yards.

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