The normal at a point on the ellipse meets the -axis at . If is the mid point of the line segment , then the locus of intersects the latus rectums of the given ellipse at the points
- (A)
- (B)
- (C)✓ Correct
- (D)
Answer: (C)
Solution
The ellipse is , so , .
Let . The normal at is:
At the -axis (): , so .
The midpoint satisfies:
From these: , .
Using :
The latus rectum of the ellipse is at .
Substituting into the locus:
Therefore, the points are .
Let . The normal at is:
At the -axis (): , so .
The midpoint satisfies:
From these: , .
Using :
The latus rectum of the ellipse is at .
Substituting into the locus:
Therefore, the points are .
JEE Advanced · 2009 · 12 Apr 2009 · Paper 2 · Single correct option