If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

# Parallel & perpendicular lines intro

CCSS.Math:

## Video transcript

let's think a little bit about two terms that you will see throughout your geometry and really mathematical career one is the idea of things being perpendicular and usually people are talking about perpendicular actually I'm misspelling it perpendicular perpendicular lines normally perpendicular lines and the idea of parallel lines parallel parallel lines so perpendicular lines are two lines that intersect at a right angle so what am i what am i talking about so let's say that this is one line right over here and that this is another line right over here we would say these two lines are perpendicular if they intersect at a right angle so they clearly intersect in order for them to intersect at a right angle the angle formed between these two lines needs to be 90 degrees and if any one of these angles is 90 degrees the rest of them are going to be 90 degrees so this is 90 degrees and these are perpendicular lines and if that's 90 degrees and that's going to be 90 degrees that's going to be 90 degrees and that's going to be 90 degrees so if any of them are 90 degrees the rest of them are 90 degrees and we have perpendicular lines if you have two lines that on a two-dimensional surface like your paper or like the screen never intersect they stay the same distance apart then we are talking about parallel lines so this line right over here and this line right over here the way I've drawn them are parallel lines they aren't intersecting they're both kind of going in the same direction but they're in there they're kind of shifted versions of each other they will never intersect with each other so these two are parallel if we have two lines that let's say they intersect but they don't intersect at a right angle so let's say we have that line and we have this line right over here and they're clearly not intersecting at a right angle then we call these neither perpendicular nor parallel lines these lines just intersect