Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Math Topics » geometry.pre-college.independent

Topic: A single term formula for calculating the circumference of ellipse
Replies: 8   Last Post: Jan 6, 2013 3:37 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ] Topics: [ Previous | Next ]
David W. Cantrell

Posts: 3,395
Registered: 12/3/04
Re: A single term formula for calculating the circumference of ellipse
Posted: Jun 14, 2009 1:31 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Shahram Zafary <shahram_zafary@yahoo.com> wrote:
> Hello dear Mr. Cantrell.
> Thanks a lot, for your really exact comments on my formula.
> I am really grateful and hope you permit me contact you again about this
> formula and some same findings that I found out before


Dear Mr. Zafary,

You are certainly welcome to contact me using my sigmaxi.net email address.

I mentioned your nice formula to Gerard Michon recently, and he has now
added a section about it on his Numericana site. See

<www.numericana.com/answer/ellipse.htm#zafary>.

Note that Gerard found a very nice alternative way of writing your
approximation: The quantity h = ((a - b)/(a + b))^2 often appears in
dealing with the perimeter of an ellipse. Using h, your approximation can
be written simply as

pi (a + b) (4/pi)^h

Although I really liked your approximation before, I like it even more in
the form above!

Best regards,
David



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.