Clicking one of the buttons marked "Circle," "Hyperbola," or "Parabola" causes a standard graph to be displayed:

• The "Circle" button sets the coefficients to represent the equation x²+y²-1=0 (the initial values).
• The "Hyperbola" button sets the coefficients to represent the equation x²-y²-1=0.
• The "Parabola" button sets the coefficients to represent the equation x²-y=0.

©2002, Addison-Wesley. All rights reserved.