The correct option is B 8√133
We know, shortest distance =|(→a−→c)⋅(→b×→d)||→b×→d|
From the given lines,
→r=^i+2^j+7^k+λ(^i+2^j+3^k) and →r=−^i−2^j+3^k+s(7^i+6^j+3^k)
we have →a=^i+2^j+7^k ;→c=−^i−2^j+3^k ;→b=^i+2^j+3^k ;→d=7^i+6^j+3^k
On solving, we have
(→a−→c)=2^i+4^j+4^k
and →b×→d=∣∣
∣
∣∣^i^j^k123763∣∣
∣
∣∣=−12^i+18^j−8^k
⇒|→b×→d|=√532
Hence, shortest distance =162√133=8√133