- #1

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Please give me the formula.

Your help is appreciated.

Thanx in advanced.

Your help is appreciated.

Thanx in advanced.

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- Thread starter Register
- Start date

- #1

- 4

- 0

Please give me the formula.

Your help is appreciated.

Thanx in advanced.

Your help is appreciated.

Thanx in advanced.

- #2

arildno

Science Advisor

Homework Helper

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As it happens, the formula is some nasty infinite series, if I'm not mistaken.

- #3

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I know that the formula to find it's area is:

20 X 7 X 3.14

I know there is a way to find it's perimeter. :p

- #4

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Register said:

I know that the formula to find it's area is:

20 X 7 X 3.14

I know there is a way to find it's perimeter. :p

It is.It is called COMPLETE ELLIPTIC INTEGRAL OF THE FIRST KIND OF ANDRE MARIE LEGENDRE.

Do you want the formula,the series exapansion??

Daniel.

- #5

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Yes, please give me the formula. ^_^

- #6

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[tex] I_{ellipse}(a,b)=:4\int_{0}^{+\frac{\pi}{2}} \sqrt{a^{2}\sin^{2}\phi+b^{2}\cos^{2}\phi} d\phi [/tex]

Daniel.

- #7

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Thank you so much. You really helped a lot. ^_^

- #8

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Register said:Thank you so much. You really helped a lot. ^_^

You're welcome... I just hope u know you can't solve that integral exactly,doncha??I'm hoping you won't be spending your whole day trying to find the antiderivative and applying the Leibniz-Newton formula...

This integral is tabulated in many engineering books...

Daniel.

- #9

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Register said:Thank you so much. You really helped a lot. ^_^

Not to be rude, but, I find it that hard to believe considering that you didn't know what an ellipse was.

- #10

rachmaninoff

- #11

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rachmaninoff said:

You're right, an oval isn't an ellipse. I've never actually seen a precise mathematical definition of an oval (i.e. I don't know what the general equation of an oval is) but it would certainly not be the same as that of an ellipse.

However in this case I suspect that Register is actually talking about an ellipse and just doesn't know the correct name for it. The area equation given as an example is after all the equation for the area of an ellipse.

- #12

BobG

Science Advisor

Homework Helper

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Try this (scroll down to equation 66) for a reasonable approximation:

http://mathworld.wolfram.com/Ellipse.html

Or this for a couple of other versions:

http://www.mechanicaldesigner.com/Ellipse.html

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