If you have Excel, here is the solution to a problem involving vectors:

http://mypeoplepc.com/members/jon8338/sitebuildercontent/sitebuilderfiles/triangulation00.xls

You input the lengths of three lines and their starting coordinates, and the 
engine calculates where they intersect ( in three dimensions).

I solved the problem when I was in the mental hospital in 1988.  It was all 
I could do to keep my sanity.  This is ~some~ of the math used to determine 
GPS coordinates.  It also calculates the two points as the result of the 
intersection of three spheres.

Jon Giffen
intrepid@bellaire.tv