Fill in the blanks:
Coordinate planes divide the space into ........ octants.

The direction cosines of a line segment $AB$ are $-2/\sqrt{17}, 3/\sqrt{17}, -2/\sqrt{17}$. If $AB = \sqrt{17}$ and the coordinates of $A$ are $(3, -6, 10)$,then the coordinates of $B$ are

If the direction cosines of two lines satisfy the equations $l-2m+n=0$ and $lm+10mn-2nl=0$,and $\theta$ is the angle between the lines,then $\cos \theta=$

All the points on the $x$-axis have

In three-dimensional space,a line $AB$ makes angles of $45^\circ$ and $120^\circ$ with the positive $x$-axis and $y$-axis,respectively. If $AB$ makes an acute angle $\theta$ with the positive $z$-axis,then $\theta = \dots^\circ$.

The direction cosines of the normal to the plane $3x + 4y + 12z = 52$ will be