If the line `vecr = (2hati+ hatj - hatk) + lambda(hati+mhatj-2hatk)` is parallel to the plane `vecr.(2hati+hatj+mhatk) = 1` then find the value of m.

Explanation

Here, `vecb=hati+mhatj-2hatk`
and `vecn = 2hati+hatj+mhatk`
If line is parallel to the plane, then
`sin theta = 0`
`rArr vecb.vecn = 0`
`rArr (hati+mhatj-2hatk).(2hati+hatj+mhatk) = 0`
`rArr 2+m - 2 m = 0`
`rArr m = 2`.