For perpendicular lines, m1m2 = -1 or m2 = -1/m1; where m1 and m2 are the slopes of the lines. Here line 1 is 2x - y - 7 = 0 y = 2x - 7; Hence m1 = 2 m2 = -1/2 Required equation y - y1 = m2(x - x1) y - (-1) = -1/2(x - 4) y + 1 = -1/2x + 2 y = -1/2x + 2 - 1 y = -1/2x + 1