Find a vector ` vec A` and its magnitude as well as direction with x-axis having initial point (P) (1,2, -1) and treminal point `Q ( 3, 2, 2) .

Explanation

` vec A =(3-1 ) hat I + (2 -2) hat j + [2 - (-1) hat k`
`= 2 hat I + 0 hat j + 3 hat k`
`= 2 hat I + 3 hat k` It means ` vec A` lies in x-z plane .
` | vec A| =sqrt (2^2 + 3^2) = sqrt 13`
If ` theta` is the angle which `vec A` makes with x-axis, then ` tan theta = 3/2 or theta = tan ^(-1) (3/2)`.