If the direction cosines of two lines are such that l+m+n=0, l^2+m^2-n^2=0 , then the angle between them is :

Step-by-step solution

If l, m, n are direction cosines of two lines are such that l+m+n=0 (i) l^2+m^2-n^2=0 ...(ii) and l^2+m^2+n^2=1 ...(iii) On solving Eqs. (i), (ii) and (iii), we get l=0, m= 1 2 and n= 1 2 Angle between these two lines = 3 or 2