A hyperbola passes through the point P 2 , 3 and has foci at ±   2 , 0 . Then the tangent to this…

A hyperbola passes through the point P2,3 and has foci at ± 2,0. Then the tangent to this hyperbola at P also passes through the point
  1. 32,23
  2. 22,33
  3. 3,2
  4. -2,-3

Solution

From the standard equation of hyperbola

±ae=± 2

As we know, b2=a2e2-1.

b2=4-a2

 Equation of hyperbola is x2a2-y24-a2=1

 It passes through 2,3 

2a2-34-a2=1

a2=t

24-t-3t-t4-t=0

8-2t-3t-4t+t2=0

t2-8t-t+8=0

 t= 8, 1

So, a2=8, 1.

a=22, 1

But for a=22, b becomes imaginary. So this case is rejected.

 Hyperbola is x21-y23=1.

The equation of the tangent at P is 2x-y3=1

Now checking each points.

Asked in: JEE Main 2017 (02 Apr)

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