To Construct a Ray:

1.  Choose the Ray tool if it’s not already active.

2.  Click to locate the endpoint of the ray. (You can click in empty space, on an existing point, on a path object such as a segment or circle, or on an intersection.)

3.  Click again to locate the point through which it travels.

If you prefer, you can use any of the Straightedge tools by pressing the mouse button at the location of the first point, dragging the mouse, then releasing the mouse button at the location of the second point.

See also
Constructing Straight Objects at Specific Angles

To Construct a Line

To Construct a Segment

Points

Path Objects

Construct Menu