The direction cosines of two lines are connected by relation `l+m+n=0` and 4l is the harmonic mean between m and n.
Then,

The direction cosines l, m, n of two lines are connected by the relation l+m+n=0 and l . m=0 then the angle between them 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 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 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

Find the direction cosines of the lines, connected by the relations: l+m+n=0 and 2l m+2ln-m n=0.

Find the direction cosines of the lines, connected by the relations: l+m+n=0 and 2l m+2ln-m n=0.