If a line is equally inclined with the coordinate axes, then the angle of inclination is

Let the line be inclined at an angle a with each of the three coordinates axes, then the direction co sines of the line are $\cos \alpha , \cos \alpha , \cos \alpha$ $3 {\cos }^2\alpha =1$

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