Talk:Cissoid

Definition is non-standard

The definition given, using the midpoint of the two given curves, seems to be non standard. The websites given as references all use the sum or difference or the radii to define the new curve. Spring Enc. of Math agrees with them as well. The definitions are basically equivalent up to scaling by a factor of 2 but the more standard one should be used. Also, the definition is not equivalent to the usual geometric definition since it assumes there is a single point corresponding to a given polar angle on both of the given curves. I'll try to resolve these issues in upcoming edits.--RDBury (talk) 08:08, 21 August 2009 (UTC)

This issue has mostly been resolved. However, the standard definition has some problems avoided by the one given at Ferréol's site. One would like to be able so say that a hyperbola is the cissoid of it's two asymptotes relative to any point on it, a very elegant theorem. But with standard definition of cissoid the statement of the theorem gets tangled up and I ended up putting a watered down version in the article. On the other hand if you start messing with the standard definition then the definition of the cissoid of Diocles gets tangled and that's got a couple millennia of tradition behind it. I don't see a good solution at the moment.--RDBury (talk) 19:59, 24 August 2009 (UTC)

Where's the Cissoid ?

Given all that math, pitiful to have a diagram that doesn't even show a cissoid. — Preceding unsigned comment added by 86.141.223.117 (talk) 15:49, 24 March 2014 (UTC)