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Glencoe Math: Course 3, Volume 2

GM

Glencoe Math: Course 3, Volume 2 View details

2. Volume of Cones

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Exercise 20 Page 603

Use the formula for the volume of a cone.

Approximately 132.5in^3

Practice makes perfect

We are told that a cone has a height of 9 inches and a base whose diameter is 7 12 inches. Let's start by drawing it.

To find the volume, we can use the formula for the volume of a cone. V= 13π r^2 h Here, r is the radius and h is the height of the cone. We already know that the height of the cone is 9 inches. To find r we can divide the diameter d by 2.

r = d/2

d= 7 12

r = 7 12/2

▼

Evaluate right-hand side

a bc=a* c+b/c

r = 152/2

a/b=1/b* a

r = 1/2 (15/2)

Multiply fractions

r = 15/4

The radius of the base is 154 inches. Let's substitute these values into the formula and calculate the volume.

V=1/3π r^2 h

r= 15/4, h= 9

V=1/3π ( 15/4)^2 ( 9)

▼

Evaluate right-hand side

(a/b)^m=a^m/b^m

V=1/3π (225/16) (9)

Multiply

V=1/3π (2025/16)

CommutativePropAdd

Commutative Property of Addition

V=1/3 (2025/16)π

Multiply fractions

V=2025/48π

Use a calculator

V=132.535940...

Round to 1 decimal place(s)

V≈ 132.5

The volume of the cone is about 132.5 cubic inches.

Subchapter links

Guided Practice p.600

Independent Practice p.601-602

H.O.T. Problems p.602

Standardized Test Practice p.602-604

Extra Practice p.603

Common Core Review p.604