A circle has the same center as an ellipse and passes through the foci `F_1a n dF_2` of the ellipse, such that the two cuves intersect at four points. Let `P` be any one of their point of intersection. If the major axis of the ellipse is 17 and the area of triangle `P F_1F_2` is 30, then the distance between the foci is (a)`13` (b)` 10` (c)` 11` (d) none of these