Basic Terms and Definitions

• A part or portion of a line with two endpoints is called a line segment.

• A part of a line with one endpoint is called a ray.

• If three or more points lie on the same line, they are called collinear points;

• otherwise, they are called non-collinear points.

• An angle is formed when two rays originate from the same endpoint.

• The rays making an angle are called the arms of the angle and the endpoint is called the vertex of the angle.