Line segment
A line segment is a part of a line defined by two endpoints. A line segment consists of all points on the line between (and including) said endpoints.
![](/img/a/geometry/lines/line-segment/line-segment.png)
Line segments are often indicated by a bar over the letters that constitute each point of the line segment, as shown above.
Dividing a line segment
A point that lies in the interior of a line segment divides the segment into 2 segments.
![](/img/a/geometry/lines/line-segment/divide-line-segment.png)
In the segment above, point C divides
into and , AC + CB = AB. This is known as the segment addition postulate.The midpoint of a line segment is a point that divides the segment into 2 congruent segments.
![](/img/a/geometry/lines/line-segment/midpoint.png)
In the figure above, point M is the midpoint of
so, ≅ .Line segments through midpoints.
A segment is a bisector of another segment if it goes through the midpoint of the segment.
![](/img/a/geometry/lines/line-segment/bisector.png)
A segment is called a perpendicular bisector of another segment if it goes through the midpoint and is perpendicular to the segment.
![](/img/a/geometry/lines/line-segment/perpendicular-bisector.png)
While there can be many segments that bisect another segment, only one segment can be the perpendicular bisector.
Line segments and polygons
The sides of a polygon are line segments. A polygon is an enclosed plane figure whose sides are line segments.
![](/img/a/geometry/lines/line-segment/polygon.png)
A diagonal for a polygon is a line segment joining two non-consecutive vertices (not next to each other).
![](/img/a/geometry/lines/line-segment/diagonal.png)
Line segments and polyhedrons
Edges formed by the intersection of two faces of a polyhedron are line segments. It takes three or more-line segments forming edges to enclose a face of a polyhedron.![](/img/a/geometry/lines/line-segment/polyhedron.png)