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jmc

algebra senior

Problem

The foci of the ellipse are and as shown below. Let be a point on the circle Line intersects the ellipse again at where the -coordinate of is positive. Find the maximum value of

problem
Solution
For the ellipse and so Then so and

Since lies on the ellipse, Then so Thus, we want to minimize

Let the center of the circle Since lies on this circle, By the Triangle Inequality, so Equality occurs when lies on line segment



Therefore, the maximum value of is
Final answer
11