Math Is Fun Forum

Al-Allo

Member

Registered: 2012-08-23

Posts: 324

Geometry definition about lines

Hi,

Here's a definition : "For every two points in space, there is a straight line passing through them, and such a line is unique."

Now, there's just a particular point which I'm not sure of. When it says : "Such a line is unique." Does it mean that the position of the line in space makes it unique ? Or in other words, I couldn't create a distinct line that is positionned at exactly the same space as the other one. The two lines would be the same. Anyway, thank you for helping my lantern !

Last edited by Al-Allo (2014-06-20 06:53:18)

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Geometry definition about lines

Hi Al-Allo

What unique means is that you cannot find any other line passing through the two points. Position of a line is not a defined term.

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PatternMan

Member

Registered: 2014-03-08

Posts: 199

Re: Geometry definition about lines

If you draw a line from point A to point B then only that line passes through A and B. If you try to turn the line then then it wont pass through both points unless it's in the exact same position which would therefore make it the same line.

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"School conditions you to reject your own judgement and experiences. The facts are in the textbook. Memorize and follow the rules. What they don't tell you is the people that discovered the facts and wrote the textbooks are people like you and me."