Question

If `O` is the origin, `O P=3` with direction ratios `-1,2,a n d-2,` then find the coordinates of `Pdot`

Answer 1

The direction cosines of `vec(OP)` are `-(1)/(3), (2)/(3) and -(2)/(3)`.
Hence, `vec(OP)=|vec(OP)|(lhati+mhatj+nhatk)`
`" "=3(-(1)/(3)hati+(2)/(3)hatj-(2)/(3)hatk)`
`" "=-1hati+2hatj-2hatk`
So, the coordinations of P are -1, 2 and -2.