Parallel & Perpendicular Lines
Perpendicular Lines
Example 3
Find the equation of the line perpendicular to y = -2 that passes through the point (4, -2).
The equation is already in slope intercept form but it has an x term of 0, making the equation y = 0x -2 . This means the slope is m = 0.
The negative reciprocal of 0 is 
The desired line will move 0 units in x for every 1 unit it rises in y. This is a vertical line, so the solution is the vertical line that passes through (4, -2). This is a line with an x coordinate of 4 at every point.
The equation of the perpendicular line is: x = 4