Ellipse

The centre of a circle C is at the centre of the ellipse E:‌

x2

a2

+‌

y2

b2

=1,a>b. Let C pass through the foci F1 and F2 of E such that the circle C and the ellipse E intersect at four points. Let P be one of these four points. If the area of the triangle PF1F2 is 30 and the length of the major axis of E is 17 , then the distance between the foci of E is: