The dc's of a pair of lines are connected by `l+m+n=0` ,`l^(2)+m^(2)=n^(2)` Then they include an angle `theta` such that `6tan^(2)theta=`

If the direction cosines of two lines are connected by the equations l+m+n=0 and l^(2) + m^(2) -n^(2)=0 , then the angle between these lines is of measure

If (l,m,n) are direction cosines of a line then L^(2)+m^(2)+n^(2)

If the direction ratios l, m ,n of the lines satisfy l-5m+3n=0, 7l^(2)+5m^(2)-3n^(2)=0 then the angle between the lines is

The direction cosines l, m and n of two lines are connected by the relations l+m+n=0 and lm=0 , then the angle between the lines is

The acute angle between the two lines whose d.cs are given by l+m-n=0 and l^(2)+m^(2)-n^(2)=0 is