Pre-Algebra Demystified

SOLUTION

V¼

4

3

pr^3

¼

4

3

 3 : 14 ð2in:Þ^3

¼ 33 :49 in:^3 (rounded)

The volume of a right circular cone can be found by using the formula

V¼ 31 r^2 h, where r is the radius of the base and h is the height of the cone.

EXAMPLE

Find the volume of the cone shown in Fig. 9-21. Usep¼ 3 :14.

SOLUTION

V¼

1

3

pr^2 h

¼

1

3

 3 : 14 ð5 in.Þ^2 9 in.

¼ 235 :5in:^3

The volume of a pyramid can be found by using the formula V¼ 31 Bh, where

B is the area of the base and h is the height of the pyramid. If the base is a

square, use B¼s^2. If the base is a rectangle, use B¼lw.

EXAMPLE

Find the volume of the pyramid shown in Fig. 9-22.

CHAPTER 9 Informal Geometry 179

Fig. 9-21.