Given two distinct lines $L_{1}and{L}_2$ are such that  $L_1$ passes through the point $(2020,2021,2022)$  and  $L_2$ passes through the point  $(2021,2022,2023)$ .If the direction cosines of both lines will satisfy the given relations  $l+m+n=0$  and  $l^2+m^2-n^2=0$.  And  $\theta$ is the angle between the lines $L_{1}and{L}_2$  where   $\theta \in [0,\frac{\pi }{2}]$ (If lines are skew then consider angle between lines means angle between their Direction ratios).
Now answer the following