Definition: In physics and mathematics, a parallel line is a line that is not intersected by any other lines. The parallel lines are perpendicular to each other in three-dimensional space. Parallel lines have no intersection point and never meet at an angle. For example: 1. A straight line (line AB) and a parallel line (line CD) are considered as the same line. 2. Two parallel lines intersecting at one point (point P), such as two lines L1 and L2, can
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