Ways To Name A Line

Line Segment

Definition: A straight line which links ii points without extending beyond them.

Endeavour this Adjust the line segment below by dragging an orangish dot on an endpoint and meet how the segment PQ behaves.

See the figure above. The line segment PQ links the points P and Q. The points P and Q are chosen the 'endpoints' of the segment. The give-and-take 'segment' typically means 'a slice' of something, and here it means the piece of a full line, which would normally extend to infinity in both directions.

A line segment is one-dimensional. It has a measurable length, but has zero width. If you depict a line segment with a pencil, examination with a microscope would show that the pencil mark has a measurable width. The pencil line is only a style to illustrate the idea on paper. In geometry however, a line segment has no width.

Naming of line segments

Line segments are unremarkably named in 2 ways:

Past the endpoints.
In the effigy higher up, the line segment would be called PQ because information technology links the two points P and Q. Recollect that points are commonly labelled with single upper-case (capital) letters. A shorthand style of writing this is This is read every bit "line segment PQ". The bar over the two letters indicates information technology is a line segment, rather than a line, which goes on forever in both directions.
By a single letter.
The segment above would exist called simply "y". Past convention, this is commonly a single lower case (modest) letter. This method is often used in the naming the sides of triangles and other polygons.

Constructions

In the constructions chapter, there are animated demonstrations of how to perform various constructions related to line segments using simply a compass and straightedge. Run across:

Copying a Line Segment.
Dividing a line segment into n equal parts
Constructing a perpendicular bisector of a line segment

Coordinate Geometry

In another branch of mathematics called coordinate geometry, the points that define a line are located on the aeroplane using their coordinates - two numbers that show where the point is positioned.
For more on this, come across Definition of a Line Segment (Coordinate Geometry).

If we know the coordinates of the two endpoints of a line segment, nosotros tin summate the distance between them, and so find the length of the line segment. See Distance between two points (coordinate geometry)