Find the angle between two lines whose direction ratios are $(2,3,6)$ and $(1,2,2)$.

Q. The acute angle between two lines whose direction ratios are $2,3,6$ and $1,2,2$ is

Q. Find the angle between the lines whose direction ratios are $3,2,-6$ and $1,2,2$.

Q. Find the acute angle between the lines in $3$-dimensional space, whose direction ratios are proportional to $6,9,18$ and $1,2,2.$

Q. Find the measure of the acute angle between the lines whose direction rations are $1,2,2$ and $-3,6,2$

Q. Find the measure of the angle between the two lines whose direction ratios are $(2,2,1)$ & $(-4,1,8)$.