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The shortest distance between the lines r⃗=2i^+3j^+4k^+λ(i^−j^+k^)\vec{r} = 2\hat{i}+3\hat{j}+4\hat{k}+\lambda(\hat{i}-\hat{j}+\hat{k}) and r⃗=5i^+5j^+5k^+μ(−i^+j^−k^)\vec{r} = 5\hat{i}+5\hat{j}+5\hat{k}+\mu(-\hat{i}+\hat{j}-\hat{k}) where λ,μ∈R\lambda,\mu \in R (set of real numbers) is:

Solution

✅ Correct Option: 1

The direction vectors i^−j^+k^\hat{i}-\hat{j}+\hat{k} and −i^+j^−k^-\hat{i}+\hat{j}-\hat{k} are proportional, so the lines are parallel.

With a⃗2−a⃗1=3i^+2j^+k^\vec{a}_2-\vec{a}_1 = 3\hat{i}+2\hat{j}+\hat{k} and b⃗=i^−j^+k^\vec{b} = \hat{i}-\hat{j}+\hat{k}, the cross product is 3i^−2j^−5k^3\hat{i}-2\hat{j}-5\hat{k}.

Distance =383=383=\frac{\sqrt{38}}{\sqrt{3}} = \sqrt{\frac{38}{3}}.

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