Locus Problem (1)
In the applet below, F is a point that is not on line d. Point D is a point that lies ON the line that passes through A and B. The pink line is the perpendicular bisector of the segment with endpoints F and D. Drag point D along the line. What do you see? Describe in detail! Feel free to alter the locations of A, B, and/or F. Then clear the trace and drag point D along the line again. Why does this occur?