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Topic: To unravel four 2D curves producing a higher invaiant
Replies: 1   Last Post: Jun 9, 2010 4:58 PM

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Posts: 2,537
Registered: 12/6/04
To unravel four 2D curves producing a higher invaiant
Posted: Jun 8, 2010 1:28 PM
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Four arbitrary points ( x1,y1,h), ( x2,y2,h), ( x3,y3,h), ( x4,y4,h),
are connected with the origin ( 0,0,0) forming 4 rays which are
projected on the x-z plane ; these projections produce a cross-ratio
CR on any cutting transversal.

How should the projection of these four points ( x1,y1) ,... (x4,y4)
move on the x-y plane so that the CR does not change? That is, what
are coordinates of the quadrilateral vertices as a function of an
arbitrary parameter t ?

Is it possible to show these on GSP?

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