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I need a forumla that rotates and elipse around it's axis...

I am using:

x = width * cos(rad)
y = height * sin(rad)
That plots out my elipse (or circle if width and height are the same). Now I need to take that elipse and rotate it somehow... I can't find a formula to do that anywhere.

Thanks for the help.
 

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If my memory serves me correctly a negative co-efficient will flip any graph for you. A negative x co-efficient should flip it on the x axis (-x^2 +2x +7). Also try swapping the x and y values as it will change the orientation of the ellipse.
 

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Here's what I would do:

1) cut your elipse in half along one axis and create a mathematical function (binomial).

2) for this example, we'll assume that rotating your model about the x-axis will yield the ellipse. So, the output of your function (the y-value) is your radius of rotation.

3) f(x) = y = radius of rotation
surface area of ellipse = PI * d = PI * 2 * f(x)
volume of ellipse = PI * r^2 = PI * [f(x)]^2
 
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