Question

Find the direction collinear of a line which makes equal angles with the positive co-ordinate axes.

Answer 1

$\alpha =\beta =\gamma$
W.K.T ${\cos }^2\alpha +{\cos }^2\alpha +{\cos }^2\alpha =1$
$3{\cos }^2\alpha =1$
${\cos }^2\alpha =\frac{1}{3}$
$\cos \alpha =\frac{1}{\sqrt{3}}$
$\therefore$ direction cosines are $\frac{1}{\sqrt{3}}.\frac{1}{\sqrt{3}}.\frac{1}{\sqrt{3}}$