The angle between the lines whose direction ratios are $a, b, c$ and $b - c, c - a, a - b$ is (in $^\circ$)

The reflection of the point $(\alpha, \beta, \gamma)$ in the $XY$-plane is:

If $\alpha, \beta, \gamma$ are the angles that a line makes with the coordinate axes,then which of the following is true?

The direction cosines of the line,which is perpendicular to the lines with direction ratios $-1, 2, 2$ and $0, 2, 1$,are respectively

If the direction ratios of two lines are $5, -12, 13$ and $-3, 4, 5$,then the angle between them is:

If $(2, 3, c)$ are the direction ratios of a ray passing through the point $C(5, q, 1)$ and also the midpoint of the line segment joining the points $A(p, -4, 2)$ and $B(3, 2, -4)$,then $c \cdot (p + 7q) = $