This is a line that curves

A line is the path of one point moving. A line has length but no width. A line is a type of geometric figure.

A line is made up of an endless number of points.

Line segments

A line segment is part of a line. Here is an example of a straight line segment:

Straight and curved lines

A line can be straight or curved. The word line usually means a straight line. A straight line is the shortest distance between two points. A straight line is the line traced by a point moving in a direction that does not change.

A curved line is sometimes called a curve. The edge of a circle is not straight and is an example of a curve.

Naming lines

Lines can get their names from any two points on the line. For example, if a line has a point named "A" on the line and a point named "B" on the line, then the line can be called either "AB" or "BA".

Sometimes, lines are also named with just one letter; for example, line A.

Two lines

Two lines can be:

  • Parallel: Two lines are parallel if they are on the same plane and they never touch.
  • Concurrent: Two lines are concurrent if they touch on one point.
  • Coincident: Two lines are coincident if they are made of the same points.
  • Perpendicular: Two lines are perpendicular if they make four right angles where they touch.
  • Skew: Two lines are skew if they are not parallel but they never touch.

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