3d Geometry

Let Q be the foot of the perpendicular from the point P(7, \(-\)2, 13) on the plane containing the lines \({{x + 1} \over 6} = {{y - 1} \over 7} = {{z - 3} \over 8}\) and \({{x - 1} \over 3} = {{y - 2} \over 5} = {{z - 3} \over 7}\). Then (PQ)², is equal to ___________.