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** Q 2127212181. ** Suppose direction cosines of two lines are given by `ul + vm + wn = 0` and `al^2 + bm^2 + cn^2 = 0`, where `u, v, w, a, b, c` are arbitrary constants and `l, m, n` are direction cosines of the lines.

For `u = v = w =1` , both lines satisfies the relation