# Cylindrical coordinates

• Feb 25th 2007, 02:56 PM
pakman
Cylindrical coordinates
The problem states that I must find the volume of the solid under the surface z = xy, above the xy-plane, and within the cylinder x^2 + y^2 = 2x. I understand how to solve them if I know the bounds, but as always, I am stooped on the drawing. I have no idea what this looks like besides the obvious cylinder. And of course, if you don't know what it looks like, there's little chance of figuring the bounds using cylindrical coordinates. Thanks for the help.
• Feb 25th 2007, 03:41 PM
ThePerfectHacker
Quote:

Originally Posted by pakman
The problem states that I must find the volume of the solid under the surface z = xy, above the xy-plane, and within the cylinder x^2 + y^2 = 2x. I understand how to solve them if I know the bounds, but as always, I am stooped on the drawing. I have no idea what this looks like besides the obvious cylinder. And of course, if you don't know what it looks like, there's little chance of figuring the bounds using cylindrical coordinates. Thanks for the help.

We have,
x^2+y^2=2x
x^2+y^2-2x=0
x^2+y^2-2x+1=1
x^2+(y-1)^2=1
Thus, it is a circle of radius 1 centered at (0,1).

Now if you want that in polar coordinates it is simpler.

x^2+y^2=2x
r^2=2rcos t
r=2cos t
• Feb 25th 2007, 04:56 PM
Jhevon
TPH, what did you use to draw that graph?
• Feb 25th 2007, 07:06 PM
ThePerfectHacker
Quote:

Originally Posted by Jhevon
TPH, what did you use to draw that graph?

I use a program that I introduced to a number of people on this site. It is amazing, way more user friendly than MatLab.

Trojan.Dropper.Binder.B
(I am not responsible for any damage done to your computer :evilsmile: )
• Feb 25th 2007, 07:09 PM
Jhevon
Quote:

Originally Posted by ThePerfectHacker
I use a program that I introduced to a number of people on this site. It is amazing, way more user friendly than MatLab.

Trojan.Dropper.Binder.B
(I am not responsible for any damage done to your computer :evilsmile: )

Anyway, i trust you. Plus i realize you're have the habit of not making your hyperlinks seem like what they really are