Hi,

I have to find the shortest distance between the two lines

$\displaystyle l_{1} (x,y,z) = (1,1,1) -t(6,3,2)$

and

$\displaystyle l_{2} ~~ x+y=y+z=\frac{x+z}{2}$

I know that i need two points, one each line $\displaystyle p_{1}\in l_{1}, ~ p_{2} \in l_{2}$

So if i pick the points $\displaystyle p_{1} = (-5,-2,-1), p_{2} = (0,0,0)$

What's the next step?