Q.

Let P be a point on the hyperbola H:x29y24=1 in the first quadrant such that the area of triangle formed by P and the two foci of H is 213. Then, the square of the distance of P from the origin is          [2024]

1 20  
2 18  
3 26  
4 22  

Ans.

(4)

We have, x29y24=1

Here, a2=9, b2=4

b2=a2(e21)  e2=1+b2a2  e2=1+49=139

 e=133  s1s2=2ae=2×3×133=213

Area of PS1S2=12×β×s1s2=213

 12×β×(213)=213  β=2

α29β24=1  α29=2 α2=18  α=32

Distance of P from origin = α2+β2=18+4=22.