What is the slope of a line parallel to this line? What is the slope of a line perpendicular to this line? Consider the line X + 7y = 7 What is the slope of a line parallel to this line? What is the slope of a line perpendicular to this line? Solution If two lines are parallel then their slopes are equal Slopes of the line can be found by writing it in the slope intercept form y = (-1/7x) +1 Comparing it to y = mx +c we get slope m = -1/7 Therefore slope of the line parallel to it is -1/7 If two lines perpendicular then the product of their slopes is -1 m1 . m2 = -1 m2 = -1/m1 = -1/-1/7 = 7 Product of a perpendicular line is 7 .