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Question
If a line makes angles of 90°, 60° and 30° with the positive direction of x, y, and z-axis respectively, find its direction cosines
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Solution
Let the direction cosines of the line be l, m, n.
Now,
\[l = \cos {90}^0 = 0\]
\[m = \cos {60}^0 = \frac{1}{2}\]
\[n = \cos {30}^0 = \frac{\sqrt{3}}{2}\]
\[\text{Therefore, the direction cosines of the line are }0, \frac{1}{2}, \frac{\sqrt{3}}{2} . \]
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