How Do You Solve a Skew Lines Distance Problem in Vector Geometry?

[thepassenger48]

Homework Statement

Given
Line1: (x,y,x)=(2,1,-1) + t(-1,0,2)
Line2: (x,y,x)=(1,1,3) + s(5,-6,-7)

The lines L1 and L2 are skew; determine points Q and R on lines L1 and L2 respectively such that ||QR|| = 2

2. The attempt at a solution
I have no idea how to even approach this question! Can someone give me a clue? Please

Thank you

 

[Dick]

Do you know how to find the closest distance between the two lines? I attempted to do it and get sqrt(16/21) which is less than 2. This means, if you imagine the geometry, that there are immensely many points on the two lines that are distance 2 apart. Are there any two in particular that you are interested in?