We start with angle A, and point B on one side of angle A.[br][br]Construct a circle with center at A that has a radius about half the length of segment AB.[br]Mark the intersections of the sides of angle A and the circle. The top is point C and the bottom is D.[br][br]Copy the circle with radius AC and center A to a circle with center at B.[br]This new circle intersects ray AB at two points. Mark the intersection of the top point, point E.[br][br][br]We will measure how far along the arc of the circle it is from C to D using the compass tool. [br]With the compass tool, mark radius CD and then copy that circle to a center at point E. [br](We want to know how far of an arc along the circle that goes through point E that would be the same distance as it is from C to D.)[br][br]Mark the lower intersection of your two circles as point F.[br]Construct line BF.[br][br]Move point B and watch what happens. [br]You can also change the size of the circle at A by moving point C if that would help you see it better.[br][br]What can you say about ray AC and line BF? Why?[br]