[R] drawing ellipses in R

[Barry Rowlingson]

On Tue, Nov 1, 2011 at 4:49 AM,  <mmstat at comcast.net> wrote:
> Hello,
>
> I have been following the thread dated Monday, October 9, 2006 when Kamila Naxerova asked a question about plotting elliptical shapes. Can you explain the equations for X and Y. I believe they used the parametric form of x and y (x=r cos(theta), y=r sin(theta). I don't know what r is here ? Can you explain 1)the origin of these equations and 2) what is r?
>

 The origin of these equations? Probably this guy:
http://en.wikipedia.org/wiki/File:God_the_Geometer.jpg

 Or maybe Euclid.

 What is r (as opposed to R)? Mathematical questions are nicely
answered by Mathworld:

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

 - a fantastic resource for maths and stats information.

Barry