Talk:Generalised circle

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I intend to add material mainly from the earlier chapters of "The Geometry of Complex Numbers" (Hans Schwerdtfeger) . It will discuss

• how the matrix permits right-handed and left-handed circles
• how under stereographic projection to the sphere these can be seen to be equivlent (because the p[oint at infinity is just another point)
• how, also under stereographic projection, a degenerate circle (a line) can also be seen to be a circle like any other
• imaginary radii
• the equations for calculating the points at which two circles intersect (and hence for determining if circles are tangent)
• transformation of generalised circles by mobius transformations

Paul Murray 02:10, 19 April 2007 (UTC)