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Question
If a line makes an angle of 30°, 60°, 90° with the positive direction of x, y, z-axes, respectively, then find its direction cosines.
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Solution
The direction cosines of a line which makes an angle of α, β, γ with the axes, are cosα, cosβ, cosγ
Therefore, D.C.’s of the line are cos30°, cos60°, cos90°
i.e., `+-(sqrt(3)/2, 1/2, 0)`
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