Difference of Focal radii of any point is equal to the length of major axis

Let the length of the latus rectum of an ellipse with its major axis along x-axis and centre at the origin be 8. If the distance between the foci of this ellipse is equal to the length of its minor axis, then which one of the following points lie on it

Theorem: The sum of the focal diatances of any point on an ellipse is constant and equal to the length of the major axis of the ellipse.

What is the sum of focal radii of any point on an ellipse equal to ?

The difference of the focal distances of any point on the hyperbola is equal to its