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# Lines, line segments, & rays

CCSS.Math:

## Video transcript

what I want to do in this video is think about the difference between a line segment a line segment a line a line and array and array and this is kind of the pure geometrical versions of these of these things and so a line segment is actually probably what most of us associate with a line in our everyday lives so a line segment is something just like that for lack of a better word a straight line but what why we call it a segment is that it actually has a starting and a stopping point so most of the lines that we experience in our everyday reality are actually line segments when we think of it from a pure geometrical point of view and I know I drew a little bit of a curve here but this is supposed to be completely straight but this is a line segment the segment the segment is based on the fact that it has a ending point and the starting point our starting point and an ending point a line if you're thinking about it in the pure geometric sense of a line is essentially its it does not stop it doesn't have a starting point and an ending point it keeps going on forever in both directions so a line would look like this a line would look like this and to show that it keeps on going on forever and in that direction right over there we draw this arrow and to keep showing that it goes on forever in kind of the down left direction we draw this our right over here so obviously yeah you know I've never encountered something that just keeps on going straight forever forever but in math that's the neat thing about math we can think about these abstract notions and so the mathematical purest geometric sense of a line is this straight thing that goes on forever now array is something in between array has a well-defined starting point so that's its starting point but then it just keeps on going on forever so then so the Ray might start over here but then it just keeps on going then it just keeps on going so that right over there is array now with that out of the way let's actually try to do the Khan Academy module on recognizing the difference between line segments lines and rays and I think you'll find it pretty straightforward based on on our classification right over here so let me get the module let me get the module going let me let me where did I put it where did I put it there you go all right so what is this thing right over here well there's two arrows on both ends so it's implying that goes on forever so this is going to be a line let's check our answer yeah it's a line now it's taking some time out correct next question all right now what about this thing well once again arrows on both sides means that this thing is going to go on forever in both directions so once again it is a line fair enough let's do another one here we have one arrow so it goes on forever in this direction but it has a well-defined starting point so it starts there and then goes on forever and if you remember that's what a ray is one starting point but goes on forever so it goes or one written think about it goes on forever and only one direction so that is a ray so let's do another question this right over here you have a starting point and an ending point or you could call this the start point in the ending point but it doesn't go on forever in either direction so this right over here is a line segment there you go so hopefully that that that gives you enough to work your way through this module and you might notice when I did this when I did this module right here there is no video and that's exactly what this video is it's the video for this module