Angle B is given and line c is the angle bisector of this angle (the red line). A point D is on the angle bisector. DE and DF are perpendicular to the sides of the angle. [br][list][br][*] Move D on the angle segment. What do you notice about the measure of DF and DE? [br][*] You can check the box next to "The measure of DF and DF" to see the measure of these two segments. [br][*] Can you form a conjecture? [br][*] You can change the measure of angle B by moving the point on the slide. Does your conjecture hold?[br][/list]