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glid02

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Here's the question:

Find the area of the surface obtained by rotating the curve

http://ada.math.uga.edu/webwork2_files/tmp/equations/18/d733a6e52ad8ca260230969bdc3f401.png

from x=0 to x=9 about the x-axis.

I'm supposed to parametrize the curve, using rcos(theta) as x and rsin(theta) as y, at least I think I am.

That would give f(x,y) = 3rcos^3(theta),rsin(theta)

Then find the partial derivatives with respect to r and theta and find their cross product. Then find the magnitude of the cross product and integrate with limits int[0-2pi] int[0-9].

Is this right? I can't find any information on the internet to do it this way and the book isn't much help either.

Thanks.

Find the area of the surface obtained by rotating the curve

http://ada.math.uga.edu/webwork2_files/tmp/equations/18/d733a6e52ad8ca260230969bdc3f401.png

from x=0 to x=9 about the x-axis.

I'm supposed to parametrize the curve, using rcos(theta) as x and rsin(theta) as y, at least I think I am.

That would give f(x,y) = 3rcos^3(theta),rsin(theta)

Then find the partial derivatives with respect to r and theta and find their cross product. Then find the magnitude of the cross product and integrate with limits int[0-2pi] int[0-9].

Is this right? I can't find any information on the internet to do it this way and the book isn't much help either.

Thanks.

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