Definition of Hyperbola
Points A and B are the foci of the Hyperbola below. Point D is the center of the Hyperbola below. Point E lies on the Hyperbola. Move points A or B to change the Hyperbola below. Then move point E about the Hyperbola. d1 is the distance from focus A to point E. d2 is the distance from focus B to point E.
What do you notice about the difference between d2 and d1? How does this applet dynamically verify our definition for a Hyperbola?