Given: C is a point on the perpendicular bisector, l, of AB. Prove: AC = BC Line l is a perpendicular bisector of line segment A B. It intersects line segment A B at point D. Line l contains point C. Use the drop-down menus to complete the proof. By the unique line postulate, you can draw only one segment, . Using the definition of , reflect BC over l. By the definition of reflection, C is the image of itself and is the image of B. Since reflections preserve , AC = BC.