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#1 20111126 16:49:48
Sufficient condition left out about parallel linesFrom: The lines must also have different yintercepts, else they are the same line. So, if you know that their slopes are the same, then you don't (automatically) know if they are parallel lines or not.  Edit: On parallel vertical lines: "a vertical line is parallel to another vertical line." No, for example, x = 2 is a vertical line, and 3x + 6 = 0 is another vertical line. These lines are not parallel to each other because they are the same line. Distinct vertical lines are parallel to each other. Last edited by reconsideryouranswer (20111126 17:01:32) Signature line: I wish a had a more interesting signature line. #2 20111126 22:28:25
Re: Sufficient condition left out about parallel linesThank you. Will review that page. "The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman #3 20120526 08:46:04
Re: Sufficient condition left out about parallel linesActually,tge definition of when two lines are parallel is when they are in the same plane and they do not intersect. I.e. A line is always parallel to itself. The limit operator is just an excuse for doing something you know you can't. “It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman “Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
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