Q.

Let the eccentricity of an ellipse x2a2+y2b2=1is reciprocal to that of the hyperbola 2x2-2y2=1. If the ellipse intersects the hyperbola at right angles, then the square of the length of the latus rectum of the ellipse is ________.          [2023]


Ans.

(2)

We have, equation of hyperbola as x21/2-y21/2=1

  eH=1+b2a2=2

So, eE=12    (Given that eE=1eH)

   Ellipse and hyperbola intersect at 90°.

  They are confocal.

Now, foci of hyperbola=(1,0)

  aeE=1a=2, b=1

So, Latus rectum of ellipse =2b2a=22=2

 Square of latus rectum is 2.