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

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 the direction ratio of two lines are given by 3lm-4ln+mn=0 and l+2m+3n=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 of two lines satisfy 2l+2m-n=0 and lm+mn+nl=0 . The angle between these lines is

If the direction cosines of two lines are (l_(1), m_(1), n_(1)) and (l_(2), m_(2), n_(2)) and the angle between them is theta then l_(1)^(2)+m_(1)^(2)+n_(1)^(2)=1=l_(2)^(2)+m_(2)^(2)+n_(2)^(2) and costheta = l_(1)l_(2)+m_(1)m_(2)+n_(1)n_(2) If the angle between the lines is 60^(@) then the value of l_(1)(l_(1)+l_(2))+m_(1)(m_(1)+m_(2))+n_(1)(n_(1)+n_(2)) is