The angle between the lines whose direction cosines are proportional to (1, 2, 1) and (2, -3, 6) is

Q. If direction cosines of two lines are proportional to $(2,3,-6)$ and $(3,-4,5)$, then the acute angle between them is

Q. Find the angle between the vectors whose direction cosines are proportional to $2,3,-6$ and $3,-4,5$.

Q. The direction cosines of the line which is perpendicular to the lines with direction cosines proportional to $(1,-2,-2)$ & $(0,2,1)$ are

Q.

The angle between two lines whose direction ratios are 1,2,1 and 2,-3,4 is:

Q. The direction cosines of the lines bisecting the angle between the lines whose direction cosines are $l_1,m_1,n_1$ and $l_2,m_2,n_2$ and the angle between these lines is $\theta$ , are