Line Segments - Concept 25,364 views

A line segment is part of a line, has fixed endpoints, and contains all of the points between the two endpoints. One of the most common building blocks of Geometry, line segments form the sides of polygons and appear in countless ways. Therefore, it is crucial to understand how to define and correctly label line segments.

If you had a line -- so if I drew in
arrows which says that they're going
infinitely, and you pick two points on
that line and you said that, wait
a minute, I'm way concerned about the
points that are in between these
two points right here, you would
be creating a line segment.
So line segment is only part of a line,
and it has fixed end points.
And by definition the line segment contains
all the points that are in between
your end points.

So to be more specific, if we had this line
segment right here, A and B, A and
B are your end points.
So I'm going to draw the arrow right there
and write that these are my end points.
And the end points are important because
that's how we label this line segment.
So we're going to call this line segment
A, B and notice I drew a little line
on top of A and B with no arrows which
tell you, the geometry student,
that this is a line segment A, B that
only goes from point A to point
B and contains all the
points in between.