The BISECT command lets you create an angle bisector to an angle formed by two selected line segments, or a perpendicular bisector to a single line segment.
Once BISECT command is executed, it will prompt in the following sequence:
asking you to select one or two line segments (either of single line entity or polyline segment). If you select only one line segment (that is, you answer with a null reply to the second prompt by pressing the space bar), then you are creating a perpendicular bisector of the line segment; otherwise, BISECT will create the angle bisector to the angle formed by the two selected line segments. However, if the two selected line segments do not form an angle because of being parallel to each other, the bisector will be a parallel line between them at the middle.
You must designate a point to the third prompt from the above sequence, to indicate the location or the start point of the bisector. BISECT also uses this point to determine which bisector is meant to create from the two possible ones for the angles formed by two line segments.
After that, BISECT will continue to prompt the following messages:
and ask you to determine the end point of the resulting bisector. You may have the following input options:
During the input to the last prompt, you may drag the resulting bisector line segment as you move the mouse pointer. In fact, this is done by calling the LINE command for the creation of a line with a fixed start point and orientation. So, there are other effective options like "DIrection", "Deflect" and "Free" appeared in the prompt. To fulfill the purpose of the BISECT command to create the bisector, however, you must not change the line constrain condition using these options.
Once the creation of a bisector is completed, BISECT will continue to cycle through the whole procedure to create the next bisector, until you press the space bar to the first prompt, or press <Ctrl/C> to terminate it.