Find the angle between the vectors with direction ratios proportional to `1,-2,1` and `4,3, 2.`

Find the angel between the vectors with direction ratios proportional to 1, -2, 1 and 4, 3, 2.

Find the angle between the vectors with direction ratios proportional to 4,-3,5 and 3,4,5.

Write the angle between the lines whose direction ratios are proportional to 1, -2, 1 and 4, 3, 2.

Find the angle between the pairs of lines with direction ratio proportional to: 2, 2, 1 and 4, 1, 8

Find the angle between the pairs of lines with direction ratio proportional to: 1, 2, -2, and -2, 2, 1

Find the angle between the pairs of lines with direction ratio proportional to: 5, -12, 13 and -3, 4, 5

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

Find the angle between the lines whose direction ratios are proportional a,b,c and b-c,c-a,a-b.

Find the angle between two lines whose direction ratios are proportional to 1,1,2 and (sqrt(3)-1),(-sqrt(3)-1),4

Find the acute angle between the lines whose direction ratios are proportional to 2:3:6 and 1:2:2.