Find an equation for the line through (2,2) that is perpendicular to y=4 then graph both lines. Since the slop is 0, is the line perpendicular to y=4 undefined?

Line y=4 is a horizontal line. Therefore any perpendicular line is vertical and have an equation x=b. For this line to go through the point (2, 2) b must be 2.

The answer is x=2.

The slope of the line y=4 is really 0. So the slope of the perpendicular line is undefined, but the perpendicular line itself is defined.

If you really need a graph of these lines, tell me.

Okay thank you. Did you simply figure this answer out by looking at the question or did you use the point slope equation to solve this? Just curious in case I have another question like this one.