The shortest distance (in units) between the lines $\frac{x+1}{3}=\frac{y+2}{1}=\frac{z+1}{2}$ and…

The shortest distance (in units) between the lines $\frac{x+1}{3}=\frac{y+2}{1}=\frac{z+1}{2}$ and $\overline{\mathrm{r}}=(2 \hat{\mathrm{i}}-2 \hat{\mathrm{j}}+3 \hat{\mathrm{k}})+\lambda(\hat{\mathrm{i}}+2 \hat{\mathrm{j}})$ is
  1. $\frac{8}{3 \sqrt{5}}$
  2. $\frac{1}{3 \sqrt{5}}$
  3. $\frac{7}{3 \sqrt{5}}$
  4. $\frac{2}{3 \sqrt{5}}$

Solution

Given lines are: $\frac{x+1}{3}=\frac{y+2}{1}=\frac{z+1}{2}$ and $\frac{x-2}{1}=\frac{y+2}{2}=\frac{z-3}{0}$ $\therefore \quad$ Required distance $=\mid \frac{\left|\begin{array}{lll} 3 & 0 & 4 \\ 3 & 1 & 2 \\ 1 & 2 & 0 \end{array}\right|}{\sqrt{(6-1)^2+(0-2)^2+(0-4)^2}}$ $\begin{aligned} & =\left|\frac{3(0-4)+0+4(6-1)}{\sqrt{25+4+16}}\right| \\ & =\left|\frac{8}{\sqrt{45}}\right| \\ & =\frac{8}{3 \sqrt{5}}\end{aligned}$

Asked in: MHT CET 2023 (12 May Shift 2)

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