The line L passes through the point A, whose position vector is i-j-5k and is parrallel to the vector i-j-4k. The line l2 passes through the point B, whose position vector is 2i-9j-14k, and is parrallel to the vector 2i+5j+6k. The point L and the point Q on L2 are such that PQ is perpendicular to both L and L2.

a. Find the length of PQ

b. Find a vector perpendicular to the plane which contains PQ and L2.

c. Find the perpendicular distance from A to the plane.