## Lines, Rays & Line Segments

A line is defined as a straight curve. Often, arrowheads are present on the ends of lines to represent continuation in both directions indefintely.

Any two points on a line may be used to
denote it as a line. Symbolically, this is expressed by an
overbar with arrowheads at each end over two letters corresponding to
points on the line. Consequently, any of the following notations
represent the line above:

The notations above are read as "Line AB," "Line BA," "Line AC," and so forth.

A ray is occasionally referred to as a half line. Rays begin at one point and continue indefinitely in a single direction after passing through another point (reference illustration below):

Similar to the methodology described above, a single arrowhead overbar is used to denote a ray. Accordingly, the ray above may be denoted as:

The notations above are read as "Ray DE" and "Ray DF" respectively. The first letter represents the endpoint while the second letter represents another point on the ray.

A line segment is the portion of a line between two points (reference depiction below):

Line segments are represented by a single overbar with no arrowheads over the letters representing the two endpoints. Consequently, the line segment above may be represented by either:

The notations above are read as "Line AB," "Line BA," "Line AC," and so forth.

A ray is occasionally referred to as a half line. Rays begin at one point and continue indefinitely in a single direction after passing through another point (reference illustration below):

Similar to the methodology described above, a single arrowhead overbar is used to denote a ray. Accordingly, the ray above may be denoted as:

The notations above are read as "Ray DE" and "Ray DF" respectively. The first letter represents the endpoint while the second letter represents another point on the ray.

A line segment is the portion of a line between two points (reference depiction below):

Line segments are represented by a single overbar with no arrowheads over the letters representing the two endpoints. Consequently, the line segment above may be represented by either:

The notations above are read as "Line Segment GH" and "Line Segment HG" respectively.

Related Topics: