Find the distance between the lines: r =( i +2 j -4 k )+λ(2 i +3 j +6 k ); r =(3 i +3 j -5 k )+μ(4 i +6 j +12 k )

Here $$\begin{aligned} & \overrightarrow{a_{1}}=\hat{i}+2 \hat{j}-4 \hat{k}, \overrightarrow{\mathrm{b}_{1}}=2 \hat{i}+3 \hat{j}+6 \hat{k} \\ & \overrightarrow{a_{2}}=3 \hat{i}+3 \hat{j}-5 \hat{k}, \overrightarrow{\mathrm{b}_{2}}=4 \hat{i}+6 \hat{j}+12 \hat{k} \end{aligned} $$ Here, $\displaystyle \overrightarrow{\mathrm{b}}_{1}$ and $\displaystyle \overrightarrow{\mathrm{b}}_{2}$ are parallel vectors.