Definition: A point on a line segment that divides it into two equal parts

The halfway point of a line segment

The halfway point of a line segment

Try this
Adjust the line segment below by dragging an orange dot on an endpoint and see how the point M
always divides the segment PQ into two equal halves.

See the figure above. The point M is the midpoint of the line segment PQ. Only a line segment can have a midpoint. A line cannot since it goes on indefinitely in both directions, and so has no midpoint. A ray cannot because it has only one end, and hence no midpoint.

When a line cuts another line into two equal parts it is called a bisector. The bisector will cut the line at its midpoint. The midpoint of a line segment can be found using a compass and straightedge. See Constructing the perpendicular bisector of a line segment.

- 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

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