Casio fx-CG10 Advanced Operation Manual page 98

Sample Solution—Extracorporeal Shockwave Lithotripsy (continued)
With the graph displayed, press
Press
The stone should be located at one focus, say ( 45, 0), and the source of the
shockwaves at the other, (45, 0).
c. Suppose that a coordinate grid is placed over the patient. An ultrasound
identifies a stone at the point ( 3, 7). Given this information, how should the
equation of the ellipse be transformed? At what location should the source of
the shock wave be placed so that the stone can be dissolved?
Answers may vary. One possible solution, when the left focus of the ellipse is
placed over the stone horizontally, is given below:
The point ( 3, 7) is 42 units to the right of and 7 units above ( 45, 0), the
location of the left focus identified in Part B. Therefore we want to shift the
entire ellipse 42 units right and 7 units above; this is done by adjusting the
centers so the equation of this ellipse would be:
Fostering Advanced Algebraic Thinking with Casio Technology
to find the other focus.
(G-Solv) and then (FOCUS).