Remark If the given line in space does not pass through the origin, then, in order to find
its direction cosines, we draw a line through the origin and parallel to the given line Now take one of the directed lines from the origin and find its direction cosines as two
parallel line have same set of direction cosines Any three numbers which are proportional to the direction cosines of a line are
called the direction ratios of the line If l, m, n are direction cosines and a, b, c are
direction ratios of a line, then a = λl, b=λm and c = λn, for any nonzero λ ∈ R