Parallel and Perpendicular Lines

Vocabulary

• parallel lines: lines that lie in the same plane and do not intersect

• perpendicular bisector: a line, ray, or line segment that intersects a segment and is perpendicular to the segment at its midpoint

• perpendicular lines: lines that intersect to form right, or 90-degree, angles

• skew lines: lines that are noncoplanar and do not intersect

• Shortest distance theorem: The shortest distance from a given line to a point not on the line is the length of the segment perpendicular to the line through the point.

• Parallel postulate: Given a line and a point not on that line, there exists exactly one line in the same plane that passes through the given point and is parallel to the given line.

• Converse of the perpendicular bisector theorem: If a point is equidistant from the endpoints of a segment, then it is on the perpendicular bisector of the segment