Browse · MATH
Printjmc
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

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
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