Axiom:Playfair's Axiom

Axiom

 * Exactly one straight line can be drawn through any point not on a given line parallel to the given straight line in a plane.

Or:


 * Given any straight line and a point not on it, there exists one and only one line which passes through this point and does not intersect the first line no matter how far they are extended.


 * This unique line is defined as being parallel to the original line in question.

Or:


 * Two straight lines which intersect one another cannot both be parallel to one and the same straight line.