Q.

If the shortest distance between the lines xλ2=y21=z11 and x31=y12=z21 is 1, then the sum of all possible values of λ is:          [2024]

1 23  
2 0  
3 33  
4 23  

Ans.

(1)

The shortest distance between the given lines is given by

d=||x2x1y2y1z2z1a1b1c1a2b2c2|(a1b2a2b1)2+(b1c2b2c1)2+(c1a2c2a1)2|

 1=||3λ11211121|(3)2+(3)2+(3)2|

 1=|(3λ)(3)+1(3)+1(3)|27

 33=333λ  or  33=333λ

 λ=0 or 63=3λ  λ=23

  The sum of possible values of λ=0+23=23.