Direction ratios of two lines are $a, b, c$ and $\frac{1}{bc}, \frac{1}{ca}, \frac{1}{ab}$. The lines are

If the direction cosines of a line satisfy the relations $l-m+n=0$ and $lm+mn-4nl=0$,then the direction cosines of the line are

If the coordinates of a point $P$ with respect to the origin $O$ are $(3, 12, 4)$,then the direction cosines of $OP$ are ..........

The angle between the lines whose direction ratios satisfy the equations $l+m+n=0$ and $l^2=m^2+n^2$ is

$A$ line $AB$ in three dimensions makes angles $45^{\circ}$ and $120^{\circ}$ with the positive $X$-axis and the positive $Y$-axis respectively. If $AB$ makes an acute angle $\theta$ with the positive $Z$-axis,then $\theta$ equals (in $^{\circ}$)

If a line makes angles $90^{\circ}, 135^{\circ}$ and $45^{\circ}$ with the positive $X, Y$ and $Z$ axis respectively,then its direction cosines are