.
The foci of the ellipse
+
= 1 are the points (-c,0) and (c,0) on x-axis, where c =
=
.
The locus of points P such that the foci subtend the right angle at point P is the circle,
centered at the origin of the coordinate plane and having the radius of
, EXCLUDING
the endpoints of its diameter that lie on x-axis.
Solved, answered and explained.