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Correct answer: 46
- Find the tangency point of the line with the circle
The circle is with centre and radius .
The line is Its distance from is so it is indeed tangent.
For a tangent point, the radius is perpendicular to the tangent. Since the line has slope , the radius has slope . So the radius through is Intersect with :
Hence
- Use midpoint condition to get from
Given is midpoint of , Thus
Also lie on the same line , and lies on that line. So they are collinear.
Given Since is midpoint of , we also have
The direction vector of the line is , whose unit vector is So moving distance along this line changes coordinates by Hence the two points at that distance from on the line are So and are these two points in some order.
- Identify which point belongs to which ellipse
Ellipse
Its centre is origin and major axis is along the -axis, so its equation is of the form For the tangent line , write it as A line is tangent to this ellipse iff Here , hence
For ellipse , tangent at is Comparing with , i.e. we get so Thus So the tangency point on such an ellipse is with first coordinate larger than second because .
Among our two candidate points, only has . Therefore
Ellipse
Its centre is origin and major axis is along the -axis, so its tangency point must have . Thus
- Compute
Now Therefore Hence
- Final answer
The required integer is
This matches the stored correct answer.
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