ShmoopTube

00:04

Lines, Segments, and Rays, a la Shmoop. [Space invaders in the background]

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This is Astrid. She’s first in line at a midnight video game release. [Astrid's parents look annoyed]

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It’s currently 9 PM. [Astrid looks embarrassed]

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With such a long time to wait, Astrid is bored out of her mind, and wonders if there’s

00:18

a way she can make her situation more interesting… [Astrid looking thoughtful]

00:21

For once in her life, she decides to relate her circumstances to a mathematical concept. [A lightbulb appears over her head]

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Astrid is a stationary point at one end of the line, so let’s call her point “A.” [Astrid stood at point A]

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Her best friend Basil just got in line at the other end; he can be point “B.” [The line fills up with people]

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More and more people keep appearing behind Basil, because the game is so darn popular… [A long queue of people]

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in fact, the line is growing… infinitely. [People keep joining to back of the line]

00:48

If Astrid never moved from the front of the line, we would say she’s standing in a ray.

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It has one endpoint, “A,” and extends infinitely in the direction of point “B.” [An arrow demonstrates the ray]

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So we would call it ray “AB.” Now imagine someone cuts in front of Astrid

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while she’s distracted. [A guy jumps to the front of the line]

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And while she was busy arguing with that person, another person cut in front of them. And so on. [People keep jumping to the front]

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If the back of the line kept growing indefinitely and the front of the line was also growing

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indefinitely as more and more people cut, we would call this line “AB.”

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That’s right; a true line, in mathematical terms, extends infinitely in both directions. [The line is shown with a double ended arrow]

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So in reality, Astrid and Basil are currently waiting in a line segment – specifically,

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a line segment with endpoints “A” and “B.”

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So it would be technically inaccurate to say they’re waiting in… line. [Astrid looked annoyed and jumping around]

01:38

Well, that killed about two minutes.

01:40

Only another two hours and 58 minutes to go until she can get her hands on Math Blasters 4: Revenge. [Astrid with her thumbs up]

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