How to Construct a Perpendicular Line Through a Point

By Rachel Kaplove

Constructing a perpendicular line through a point is something that will require you to pay close attention to the angle. Construct a perpendicular line through a point with help from a professional private tutor in this free video clip.


Hi, I'm Rachel, and today we're going to be going over how to construct a perpendicular line through a point. So, let's say we have a point like this, and it's gonna need to be on a line in order to find something that's perpendicular to it. So, in order to find something that's perpendicular, we want to find something that forms a 90 degree angle, like this. So, if we go straight 90 degrees, we form a perpendicular line from that point. Now if you're talking about doing this on a graph, you want to find a line that is the negative reciprocal. What does that mean, of the slope? So, this means that if one line has a slope of y equals 3x plus four, a line that's going to be perpendicular to that point is going to have the negative reciprocal, so y equals negative one-third x, and anything on that line will be perpendicular to this point. I'm Rachel, and thank you for learning with me today.

About the Author

Rachel Kaplove has worked as a professional private tutor since 2005. Specializing in Math and Science, she tutors students from the second grade level to advanced high school honors levels.