Line Segment Bisector

In general 'to bisect' something means to cut it into two equal parts. The 'bisector' is the thing doing the cutting.

With a line bisector, we are cutting a line segment into two equal lengths with another line - the bisector. In the figure above, the line PQ is being cut into two equal lengths (PF and FQ) by the bisector line AB.

If AB crosses at a right angle, it is called the "perpendicular bisector" of PQ. If it crosses at any other angle it is simply called a bisector. Drag the points A or B and see both types.

For obvious reasons, the point F is called the midpoint of the line PQ

See also Angle bisector.

How to bisect a line segment

Obviously, one way to bisect a line segment is to measure its length, divide that by two and mark the midpoint.

But you can do it without any measurement at all using just a compass and straightedge using techniques developed thousands of years ago by the Greeks. For an animated demonstration of how to do this see Perpendicular bisector of a line segment

Other line topics

• Point definition
• Line definition
• Vertical lines
• Horizontal lines
• Line segment
• Midpoint of a line
• Ray
• Angle
• Opposite rays
• Intersection
• Parallel lines
• Transversal
• Line bisector
• Perpendicular bisector
• Coplanar
• Collinear points
• Plane