Your computer monitor or the screen of your smartphone is a great way to visualize parallel and perpendicular lines.
Jenn, Founder Calcworkshop®, 15+ Years Experience (Licensed & Certified Teacher)
Parallel Lines never intersect, whereas two lines that are perpendicular meet at a right angle, 90°.
The top and bottom or left and right sides of a computer monitor are parallel and each corner represent a right angle, so this shows where two lines are perpendicular.
But we aren’t always able to determine these aspects of two lines just by looking at them. Yes, we can graph each line and “inspect,” but this isn’t always accurate, as Purple Math so clearly states.
Graphical Representation of Parallel and Perpendicular Lines
So how do you determine if two lines are parallel or perpendicular or neither?
Calculate their slopes and compare!
Parallel lines have the same slope, whereas perpendicular lines have negative, reciprocal slopes.
Okay, so you may be thinking….determining if two lines are parallel (same slope) is really straightforward, but perpendicular…. I’m a little confused.
Don’t worry!
All this means is that if two lines are perpendicular, then they will have opposite signs and one is the “flip” of the other.
Together we will easily calculate, using our slope formula, the slope of each line and determine if two lines are parallel or perpendicular. And we will also be able to compare equations of lines and learn how to identify if the lines have a parallel or perpendicular slope.
Parallel Perpendicular Lines – Video
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