A line L1 with direction ratios −3,2,4 passes through the point A(7,6,2) and a line L2 with directions ratios 2,1,3 passes through the point B(5,3,4). A line L3 with direction ratios 2,−2,−1 intersects L1 and L2 at C and D, resectively. The lenth CD is equal to:_______
