Let an ellipse with centre (1,0) and latus rectum of length 1 2 have its major axis along x-axis. If its minor axis subtends an angle 60° at the…
JEE Main 2023 — Mathematics Coordinate Geometry
2023integermedium
Let an ellipse with centre (1,0) and latus rectum of length 21 have its major axis along x-axis. If its minor axis subtends an angle 60∘ at the foci, then the square of the sum of the lengths of its minor and major axes is equal to _______.
Official previous-year question
Held on 15 Apr 2023 · Verified 6 Jul 2026.
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Solution
Given,
An ellipse with centre (1,0) and latus rectum of length 21 have its major axis along x-axis
And its minor axis subtends an angle 60∘ at the foci,
So, on plotting the diagram we get,
Now from diagram we get,
a2b2=21⇒b2=4a...(1)
And tan30∘=aeb
⇒(31)2=(aeb)2
⇒31=a2−b2b2
⇒a2−b2=3b2
⇒b2=4a2.......(2)
Now from equation (1)&(2) we get,
⇒a=1,b2=41⇒b=21
Hence, (2a+2b)2=9
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