Big Ideas Math: Modeling Real Life, Grade 8
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Big Ideas Math: Modeling Real Life, Grade 8 View details
2. Volumes of Cones
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Exercise 16 Page 437

Use the formula for the volume of a cone.

≈ 65.4 in.^3

Practice makes perfect

We want to find the volume of a cone.

We can use the formula for the volume of a cone. V=1/3 B h Here, B is the area of the base and h is the height of the cone. Since the base is a circle, the area of the base will be equal to π r^2, where r is the radius. V= 1/3 π r^2 h We are given that the height of the cone is 10 inches and the diameter of the base is 5 inches. Note that if we divide the diameter by 2, we get the radius of the base. r=5/2= 2.5in. Let's substitute r= 2.5 and h= 10 into the formula and calculate the volume.
V=1/3π r^2 h
V=1/3π ( 2.5)^2 ( 10)
Evaluate right-hand side
V=1/3π(6.25)(10)
V=1/3π(62.5)
V=1/3(62.5π)
V=62.5π/3
V=65.449846...
V≈ 65.4
The volume of the cone is about 65.4 cubic inches.