Many geometric drawing tasks use the perpendicular bisector of a segment to measure various things. This is useful because each point of the perpendicular bisector is equidistant from the end points of the segment.

Let's draw the perpendicular bisector for the line segment AB.

1. Draw the line segment's endpoints A and B as centres of intersecting circular arcs with the same radius.
2. Draw a line that passes through the intersections of the two circular arcs. This straight line is the perpendicular bisector of segment line AB.