you can do this as shells or washers.
with shells of thickness dy, remember that the volume of a shell is 2πrh. So, draw the region, and
∫[0,2] 2πrh dy
For discs with holes, of thickness dx, work with
∫[1,2] π(R^2-r^2) dx
your job is to examine the region in question and figure out R,r,h as required.
Set up, but do not evaluate, the integral which gives the volume when the region bounded by the curves y = Ln(x), y = 2, and x = 1 is revolved around the line y = −2.
2 answers
Ugh Steve why