Homework Help: Volume of

1. May 9, 2005

cmab

Can anybody help me find the volume y=sinx, bounded by the y axis, and the line y=1. The axis of revolution is the line y=1.

I tried so many times and I cant find the correct answer, in the sheet it says (pie^2)/2 - 2pie

2. May 9, 2005

OlderDan

What method are you using, and what are you integrating?

3. May 9, 2005

cmab

[int a=0 b=1] pie(arcsiny)^2 dy

disk method.

4. May 9, 2005

cmab

I don't know if I did good, cause I'm uncapable of integrating it.

5. May 9, 2005

p53ud0 dr34m5

try cylindrical shell method

6. May 9, 2005

cmab

In my paper it says use disk method.

7. May 10, 2005

OlderDan

I don't think you are looking at it right. As I see it, the radius of a disk centered on the axis of rotation is 1 - sin x and the thickness of the disk is dx. The integral runs from the y-axis (x = 0) to the value of x at the intersection of y = 1 with y = sin x.

8. May 10, 2005

jtox

I was thinking the same thing, and maybe it's just me, but if you finish integrating that, won't you get an answer that's off somewhat? (I think by about +$$\textstyle{\frac{\pi^2}{4}}$$, otherwise I'm totally and utterly wrong :yuck: )
cmab, can you doublecheck that answer that your book states?

Last edited: May 10, 2005
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook