Example 2: (pg: 425) Find the volume of the solid that is obtained when the region under the curve over the interval [1, 4] is revolved about the x-axis.
11–18 Find the volume of the solid that results when the region enclosed by the given curves is revolved about the x-axis. " 11. y = '25 − x2, y = 3 12. y = 9 − x2, y = 0 13. x = 'y, x = y/4 14. y = sin x, y = cos x, x = 0, x = "/4 [ Hint: Use the identity cos 2x = cos2 x − sin2 x.] 15. y = e x , y = 0, x = 0, x = ln 3 16. y = e−2x, y = 0, x = 0, x = 1 17. y = 1'4 + x2 , x = −2, x = 2, y = 0 18. y = e3x '1 + e6x , x = 0, x = 1, y = 0
2: Volumes by Washer Method (pg: 426) Washer Washers
Doughnuts are like Washers
Volumes by washers: Perpendicular to the x-axis Perpendicular to the y-axis
Example 4: (pg: 426) Find the volume of the solid generated when the region between the graphs of the equations and g(x)=x over the interval [0, 2] is revolved about the x-axis.
Volumes by disks and washers perpendicular to the y-axis (page:426)
Equation (8) Figure 6.2.14 (p. 427) Equation (7)
Example 5: (pg: 427) Find the volume of the solid that is obtained when the region enclosed by the curve y=2, and x=0 is revolved about the y-axis.