System of three unit vectors which start from one common point (peak point or origin). A trihedral defines a co-ordinate system in space by the three straight lines (as co-ordinate axes) which run along the unit vectors. In case of pairwise orthographic unit vectors (orthographic trihedral) we have especially a cartesian co-ordinate system.
If one is able to illustrate the three unit vectors e1, e2, e3 in this order by using thump, forefinger and middle finger of the right hand (right-hand-rule), the Trihedral is called right system otherwise left system.
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cartesian co-ordinates |
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vector |