Subject:
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RE: need Help finding a co-ordinate
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Newsgroups:
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lugnet.cad
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Date:
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Mon, 11 Sep 2000 17:46:33 GMT
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Viewed:
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1313 times
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Ralph Hempel writes:
> If the 4 points ARE coplanar, then
> throw out one of the points and figure out the equation of
> the plane described by the three points. This can be
> found in any decent algebra text.
And in case you don't have a text handy...
lets call our points A=(a1,a2,a3), B, and C.
Find the cross product of AB x AC = N = <n1,n2,n3> to get the normal vector
to the plane. Then
n1(x-a1) + n2(y-a2) + n3(z-a3) = 0
is the equation of the plane. Any point in the plane will satisfy this eq.
HTH,
--Bram
Bram Lambrecht
BXL34@po.cwru.edu
http://home.cwru.edu/~bxl34/
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Message is in Reply To:
 | | RE: need Help finding a co-ordinate
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| (...) Ummm, if you mean co-planar, there is no guarantee that 4 points are coplanar in 3-space. however, 3 points are always coplanar. If the 4 points ARE coplanar, then throw out one of the points and figure out the equation of the plane described (...) (26 years ago, 11-Sep-00, to lugnet.cad)
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