L has the parametric form x=s+1, y=s-2,z=2s+3 and P=3x-2y+z=1 and P'=x-y-2z=1. Find the points m on L and m' on L' such that the distance between them is minimised, this will occur when the line from m' to m is perpendicular to both L and L'

Would the L and L' be vectors or planes?

Thankyou