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

Current time:0:00Total duration:1:55

CCSS.Math:

any pair of points can be connected by a line segment that's right connect two pairs of black points in a way that creates two parallel line segments so let's see if we can do that so I could create one segment that connects these this point to this point and then another one that connects this point to this point and they look pretty parallel in fact I think this is the right answer if we did it another way if we had connected that point to that point if we connected that point to that point and this point to this point then it wouldn't look so parallel these clearly if they were to keep these were to keep going they would intersect at some point so let me set it back up the way I did it the first time let me make these two points let me make these two points parallel and these are line segments because they have two endpoints they each have two endpoints and they continue forever well they don't continue forever they continue forever in no directions in 0 directions if it was array it would continue forever in one direction if it's a line it continues forever past both of these points in fact it wouldn't have endpoints they would just continue forever in both of these both of these directions let's do one more drag the Ray so it has an endpoint at a so we want to make its endpoint a day where the Ray terminates and goes through one of the other black points the Ray should also be parallel to the pink line so have two options I could make it go through this black point there's clearly not parallel in fact it looks perpendicular here so let's may try to make it go through this point well yes when I do that it does indeed look like my Ray is parallel to the pink line and this is array because it has one endpoint this is where the reiter Minh eighths it's an endpoint it literally ends there and it continues forever in one direction in this case the direction is to the right it continues forever to the right so it continues forever in one continues forever in one direction