The length of the perpendicular drawn from the point (2, 1, 4) to the plane containing the lines

 $\vec{r}=\left(\hat{i}+\hat{j}\right)+\lambda \left(\hat{i}+2\hat{j}-\hat{k}\right)$

 $\vec{r}=\left(\hat{i}+\hat{j}\right)+\mu \left(-\hat{i}+\hat{j}-2\hat{k}\right)$ is