Q.

Let a hyperbola passes through the focus of the ellipse x225+y216=1. The transverse and conjugate axes of this hyperbola coincide with the major and minor axes of the given ellipse, also the product of eccentricities of given ellipse and hyperbola is 1, then                      [2006]

1 the equation of hyperbola is x29-y216=1  
2 the equation of hyperbola is x29-y225=1  
3 focus of hyperbola is (5,0)  
4 vertex of hyperbola is (53,0)  

Ans.

(1, 3)

For the given ellipse x225+y216=1e=1-1625=35

Eccentricity of hyperbola =53

Let the hyperbola be x2A2-y2B2=1 then

B2=A2(259-1)=169A2      x2A2-9y216A2=1

As it passes through focus of ellipse i.e. (3,0)

  we get A2=9B2=16

  Equation of hyperbola is x29-y216=1

Its focus is (5, 0) and vertex is (3, 0)