The perpendicular bisector of a line segment is a line that passes through the midpoint of the segment (it [i]bisects[/i] it, or cuts it into two equal pieces) and it makes a [math]90^{\circ}[/math] angle with it (is [i]perpendicular [/i]to it). [br]In the sketch below the red line pb is the perpendicular bisector of the line segment AB. A and B can be moved to change the segment and D is a point on the perpendicular bisector.[br]Draw the segments joining D to A and B.