Science:Math Exam Resources/Courses/MATH101/April 2012/Question 02 (b)/Hint 1

Use the method of washers (cross-sections).

Look at the sketch at part a), the cross-sections are formed by intersecting the region R by a straight line x=c where -1<c<2, and then rotating the line segment about the axis y=5. The result should look like a washer.

To find the volume of revolution, find the area of this washer as a function of x and then integrate from the left to right endpoint of the region.