# Thread: area of the surface of rotation for a parametric curve.

1. ## area of the surface of rotation for a parametric curve.

this is actually something that my professor decided not to cover (it's not specifically on the department requirements.) the text has a formula for working these types of problems.

thanks for the help

2. ## Re: area of the surface of rotation for a parametric curve.

I can't understand what you have written. You say "the exact area of the surface obtained by rotating the given curve around the x-axis." But give two functions- each is given as a function of "t" but you have "$\theta$" in the formulas.

3. ## Re: area of the surface of rotation for a parametric curve.

Hey bkbowser.

Just to clear things up, is the t meant to be theta and is the a meant to be the radius r?

If you want to get this in the form of pi*f(x)^2*dx, then you will need to use a Jacobian transformation to go from (r,theta) space to (x,y) space.

Are you trying to the difference in volume where you rotate two functions to obtain the volume in-between those objects (as you said, a 'washer' problem)?

Please give us the equations in terms of either (r,theta) or (x,y) only as to avoid confusion.