Three Dimensional Geometry: JEE Main 2021 Mathematics question

Let the foot of perpendicular from a point P(1, 2, $-$1) to the straight line $L:{x \over 1} = {y \over 0} = {z \over { - 1}}$ be N. Let a line be drawn from P parallel to the plane x + y + 2z = 0 which meets L at point Q. If $\alpha$ is the acute angle between the lines PN and PQ, then cos$\alpha$ is equal to ________________.