Here's the question.
If P is any point on the hyperbola and PR and PS are drawn parallel to the asymptotes, the dPR x dPS = constant. Show this is true for the hyperbola:
x^2/4 - y^2/4 = 1
by choosing three different points for P. Can you prove the general case?
P.S. I'm assuming that dPR means the distance from P to R.
Here's the diagram
Thanks in advance.