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What Are Parallel Lines?
Angles between intersecting lines
Two lines that are stretched into infinity and still never intersect are called coplanar lines and are said to be parallel lines. If we have two lines they don't have to be parallel and have a third line that crosses them as in the figure below - the crossing line is called a transversal:. If we draw to parallel lines and then draw a line transversal through them we will get eight different angles.
In geometry , parallel lines are lines in a plane which do not meet; that is, two straight lines in a plane that do not intersect at any point are said to be parallel. Colloquially, curves that do not touch each other or intersect and keep a fixed minimum distance are said to be parallel. A line and a plane, or two planes, in three-dimensional Euclidean space that do not share a point are also said to be parallel. However, two lines in three-dimensional space which do not meet must be in a common plane to be considered parallel; otherwise they are called skew lines. Parallel planes are planes in the same three-dimensional space that never meet. Parallel lines are the subject of Euclid 's parallel postulate.