Points, Lines, Segments, Angles etc.

Points and Lines

A point is a specific location in space. A point is drawn as a dot. Often we label a point with some letter. We would say "Point A" for instance.

Above you see three points labeled A, B and C.

Lines are something you have seen in Algebra. Straight lines go on infinitely far in both directions. Closely related to the line are rays and line segments.

A ray is what we can think of as "half a line". A ray starts at a given point and then goes of to infinity in one direction.

A line segment is just a small part of a line. It starts at one point and ends at another.

In the picture above we see the difference between a line, a ray and a segment. The line is the figure at the top. As we can see it goes on for ever. The figure in the middle is a ray. It starts at a point and then moves off to the top-right. The line segment is all the way at the bottom.

Example showing several line segments and their labels

We will be using line segments a lot in later sections. We will label segments by recording the endpoints. For example:

In this diagram we see several line segments:

• Segment AP is the line segment connecting A and P. Note that we can also call this segment PA.
• Segment AB (or BA if you like) runs vertically.
• Segment BP is the third segment shown.

AM, MB and MP are also segments. There is also a line in this picture. It is labeled r.

Worksheet

Do the following Lines and Line Segment Worksheet to check that you have remembered what lines and segments are.

Resources

Ouside source: [Math League: Basic Terms] Click on the link and look at the examples.