Find the angle between the lines whose direction cosines has the relation `l+m+n=0 and 2l^(2)+2m^(2)-n^(2)=0`.

Find the angle between the lines whose direction cosines have the relations l+m+n=0 and 2l^(2)+2m^(2)-n^(2)=0 .

The angle between the lines whose direction cosines satisfy the equation l+m+n=0 and l^(2)=m^(2)+n^(2) is

Find the angle between the line whose direction cosines are given by l+m+n=0 and 2l^(2)+2m^(2)-n^(2)-0