The straight line L1 with vector equation r=a+tb cuts the plane 2x-3y+6z=6 at the right angles at the point (5,1,-1)

The Line L1= 5i+j-k+t(2i-3j+k). Another straight line, L2, has vector equation r=s(i+3j+2k)

Find the angle between L1 and L2, giving your answer to the nearest degree.

prove that L1 and L2 do not meet, given L2 cuts the plane at the point (-1.2,-3.6,-2.4)