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General Science => General Science => Topic started by: Donnah on 06/05/2004 15:28:24

Title: Calculating the surface area of an ellipse?
Post by: Donnah on 06/05/2004 15:28:24

Hey everyone!
Donnah's son again [:D]
New question, although a bit more mathmatical in nature.
In my calculus class, we have been debating a bit about how to find the surface area of an ellipse.
I have a pretty good theory as to how to get the perimeter, but still the SA eludes me.  Anyone Know?
Thanks
-Steve

Title: Re: Calculating the surface area of an ellipse?
Post by: Dan B on 06/05/2004 16:34:16

Integrate your circumference from 0 to 2pi.

Title: Re: Calculating the surface area of an ellipse?
Post by: Ylide on 07/05/2004 18:38:34

Or, if line integral aren't your thing, you can do it with a basic cartesian equation of the ellipse.

Center the ellipse on the origin and write it as an equation, X^2/a^2 + Y^2/b^2 = 1.  (where a is the X-axis radius and b is the y-axis radius)  Solve for Y = f(x)  and you have the equation for one half of the ellipse.  Integrate the equation f(x) over the length in the x-axis and you have the area under the top half of the ellipse.  Now double it, and there's your answer.



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Title: Re: Calculating the surface area of an ellipse?
Post by: chris on 14/05/2004 04:46:05

Wow, nicely done !

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

Title: Re: Calculating the surface area of an ellipse?
Post by: Ylide on 30/06/2004 14:30:07

A year and a half of calculus had to be good for something.



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