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From: iau@ukc.UUCP
Newsgroups: net.math
Subject: moRe: Conic sections (new problem)
Message-ID: <660@eagle.ukc.ac.uk>
Date: Fri, 31-Jan-86 07:22:07 EST
Article-I.D.: eagle.660
Posted: Fri Jan 31 07:22:07 1986
Date-Received: Sun, 2-Feb-86 01:01:54 EST
References: <1165@homxb.UUCP> <557@well.UUCP> <532@well.UUCP> <11591@ucbvax.BERKELEY.EDU>
Reply-To: iau@ukc.UUCP (Ian Utting)
Organization: U of Kent at Canterbury, Canterbury, UK
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Xpath: ukc eagle

Having seen half a dozen replies to the original posting, all giving
information I found in Analytical Geometry textbooks going back 150 years, I
thought I'd try a slight change of direction. So:

Does anyone know (or know where to find) expressions for the coefficients of
the (oft quoted) general second order equation in terms of the radii
($r_{major},r_{minor}$), center ($x_c,y_c$) and rotation ($theta$) of a
circle or ellipse (I'm not interested in the other conics). I've
found/discovered/guessed the forms with center and radii, but when I
try to add rotation, I'm stumped.

I'd tell you why I'm interested in this, but given the recent flames about
what should (or shouldn't) be in this group, I don't think you'd want to
know.

	Ian Utting	iau@ukc.uucp
(From the above, you'll have guessed that I'm no mathematician).