From scratch:
If l1,m1,n1 and l2,m2,n2 are the sets of direction cosines for two
lines, the angle between the lines, say A, is given by
cos A = l1*l2 + m1*m2 +n1*n2
For a line with azimuth Az and plunge Pl, where x,y,z axes are
taken along N,E,down, the direction cosines are
l = cos Pl cos Az
m = cos Pl sin Az
n = sin Pl
All very Excel-able. (Sorry about the l's ('ell') and the 1's (one).)
Bill
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Dr W H Owens E-Mail: [log in to unmask]
School of Earth Sciences Phone: +44-(0)121 414 6137
University of Birmingham Fax: +44-(0)121 414 4942
Edgbaston
Birmingham B15 2TT
UK
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