Question
The foci of the ellipse 
+ 
= 1 and the hyperbola 
– 
= 
coincide. Then the value of b2 is-
- 9
- 1
- 5
- 7
Hint:
find the foci of both the curves and equate them.
The correct answer is: 7
7
given, value of a2 is 144/25 and b2 is 81/25
e= √(1+ b2 / a2 )= 15/12
foci = (ae,0) = (3,0)
a for ellipse = 4
focus = 4e,0
4e= 3
e=3/4
=> b2= 16(1-9/16) = 7
focus of ellispe = ae,0
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