Assertion(A): If the Dr’s of a line are (-6,2,3) then the angles made by the line with coordinate axis are  ${\cos }^{-1}(-\frac{6}{7}),{\cos }^{-1}\left(\frac{2}{7}\right),{\cos }^{-1}\left(\frac{3}{7}\right)$  
Reason (R): The Dc’s of a line $\overline{op}$  are $(\frac{x}{r},\frac{y}{r},\frac{z}{r})$   where  $\left|\overline{op}\right|=r$  and  $p=(x,y,z)$