Page 687 - Basic College Mathematics with Early Integers

664 C HAPTE R 9 I GEOMETRY

PRACTICE 4 Example 4 Approximate the volume of a cone that has a height of 14 cen-
timeters and a radius of 3 centimeters. Use 3.14 for p. Give an
Find the volume of a square-
based pyramid that has a exact answer and an approximate answer.
3-meter side and a height of
5.1 meters.

5.1 m 14 cm

3 cm

3 m

Solution: Using the formula for volume of a cone, we have
1
p r
V = # # 2 # h
3
1 2 #
p (3 cm)
= # # 14 cm Replace r with 3 cm and h with 14 cm.
3
= 42p cu cm
Thus, 42p cubic centimeters is the exact volume. To approximate the volume, use
the approximation 3.14 for p.
#
V L 42 3.14 cu cm Replace with 3.14.
p
= 131.88 cu cm
The volume is approximately 131.88 cubic centimeters.
Work Practice 4

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Answer
4. 15.3 cu m