If x2−y2=0, lx+2y=1form a isosceles triangle, then l=

The given lines are x+y=0   …… (1)  x−y=0   …… (2)And  lx+2y=1    …… (3)Equations (1) and (2) represents two perpendicular lines, and the third line makes an angle  with the line (1) and line (2)  Hence, tan45°=m1−m21+m1m2=−l2−11−l2=l+22−l It implies that l=0