28 Let R be the region bounded by yx yx and x1 Compute the v

28. Let R be the region bounded by y=x, y=-x, and x=1. Compute the volume of the solid formed by revolving R about the given line
(a) the x-axis (b) the y-axis (c) y=1 (d) y=-1

For C and D, how do you find the outer and inner radius.

Here\'s what I have for (c):

Since y=1 is higher on the y-axis than the region R, the outer radius formula becomes 1-x and the inner radius formula is 1-0 since the bottom of the \"donut hole\" is y=0 (x-axis).

For (d):

Since the shaded region R is higher on the y-axis then the formula for the outer radius is x-(-1) = (x+1). For the inner radius the formula is 0-(-1) to become (0+1) for inner radius.

The answers to both should be the same for revolution points y=1 and y=-1 but my answers are different.

Solution

the answer is in this site

http://www.chegg.com/homework-help/calculus-early-transcendental-functions-3rd-edition-chapter-5.2-problem-28-solution-9780072869538