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Unformatted text preview: z 3z 1 z 3z 2 Arg z 4z 1 z 4z 2 (mod 2 ) 0 or . In other words, the crossratio z 3z 1 z 3z 2 / z 4z 1 z 4z 2 is real. (b) If z 1 , z 2 and z 3 are collinear, then again the crossratio is real. The argument is reversible. (iii) Assume that A, B, C, D are distinct points such that the crossratio r = z 3z 1 z 3z 2 / z 4z 1 z 4z 2 is real. Now r cannot be 0 or 1. Then there are three cases: 63...
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This note was uploaded on 12/19/2011 for the course MAS 3105 taught by Professor Dreibelbis during the Fall '10 term at UNF.
 Fall '10
 Dreibelbis

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