Find the shortest distance between the lines `vecr=(hatii+2hatj+hatk)+lamda(2hati+hatj=2hatk) and vecr=2hati-hatj-hatk+mu(2hati+hatj+2hatk)`.

Explanation

Here,
`veca_(1) = hati+2hatj+hatk, vecb_(1)= hati-hatj+hatk`
`veca_(2)=2hati-hatj-hatk, vecb_(2)=2hati+hatj+2hatk`
`:. veca_(2)-a_(1)=hati-3hatj-2hatk`
`vecb_(1) xx vecb_(2) = |{:(hati,hatj,hatk),(1,-1,1),(2,1,2):}| = - 3 hati+3hatk`
Shortest distance between two lines
`= |{:((veca_(2)-veca_(1)).(vecb_(1)xxb_(2)))/(|vecb_(1)xxvecb_(2)|):}|`
`= |{:((hati-3hatj-2hatk).(-3hati+3hatk))/(|-3hati+3hatk|):}|`
`= |{:(-3-6)/(sqrt(9+9)):}|=(9)/(3sqrt(12)) = (3)/(sqrt(2))`