The equation of lines passing through (1,-1,1) and havingdirection cosines as (2,3,1,) are
x−1
2
=
y+1
3
=
z−1
1
=r From the above equations, we get x=2r+1,y=3r−1,z=r+1 The points, (2r+1,3r−1,r+1) lie on plane. These points satisfy the equation of the plane, 3(2r+1)+4(3r−1)+5(r+1)+19=0 6r+3+12r−4+5r+5+19=0 23r+23=0 r=−1 So, the point is, (−2+1,−3−1,−1+1)=(−1,−4,0) Now the required distance is, √(−2)2+(−3)2+12=√4+9+1 =√14