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(D) Let the direction cosines of the line be $l, m, n$. Since the line makes equal angles $\alpha$ with the coordinate axes,we have $l = \cos \alpha$,

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$\cos^{-1}(1/\sqrt{3})$

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(D) Let the direction cosines of the line be $l, m, n$. Since the line makes equal angles $\alpha$ with the coordinate axes,we have $l = \cos \alpha$,$m = \cos \alpha$,and $n = \cos \alpha$. We know that for any line,$l^2 + m^2 + n^2 = 1$. Substituting the values,we get $\cos^2 \alpha + \cos^2 \alpha + \cos^2 \alpha = 1$. $3 \cos^2 \alpha = 1$. $\cos^2 \alpha = 1/3$. $\cos \alpha = 1/\sqrt{3}$ (taking the positive value for the acute angle). Therefore,$\alpha = \cos^{-1}(1/\sqrt{3})$.

If a line in a plane makes equal angles with the coordinate axes,then the angle made by the line with any one axis is equal to .........

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