It is a bisector.
A Segment Bisector
A line that intersects a segment at its midpoint bisects the segment.
I line that intersects a segment at its midpoint.
perpendicular bisector
bisector
It is called a bisector.
Such a line is called a perpendicular bisector.
It is a bisector.
A line that is perpendicular to the segment of a plane and passes through the midpoint.
Take a compass, extend it about 3/4 of the length of the segment. Then from one end of the segment, draw a 180 degree arc. From the other end draw another arc. Connect the points where the arcs intersect. Where the line intersects with the segment is the midpoint of the segment. That is how you bisect a segment to find the midpoint - geometrically.
A plane intersects a line at a point, and i plane intersects another plane at a line.
All bisectors intersect the line segment at the midpoint. There can be multiple bisectors, intersecting at the midpoint at different angles, but they all intersect the line segment at its midpoint. The midpoint separates the line segment into two equal halves.