If C Is The Centre And A, B Are Two Points On The Conic 4x2 + 9y2 – 8x – 36y + 4 = 0 Such That ∠ACB = π/2 Then CA–2 +CB–2 is Equal To  

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Question

 

If C is the centre and A, B are two points on the conic

4x2 + 9y2 – 8x – 36y + 4 = 0 such that ∠ACB = π/2 then CA–2 +CB–2 is equal to  

Solution

Correct option is

 

We have, 

      

   

Clearly, the coordinates of C are (1, 2). 

Suppose CA makes an angle θ with the major axis. 

Then, the coordinates of A and B are 

      

          

          

Since A and B lie on (i). Therefore,  

       

and, 

       

and, 

          

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