Find the equation of the hyperbola having its foci at $(0, \pm \sqrt{14})$ and passing through the point P(3, 4).
Given: Foci at $(0, \pm \sqrt{14})$ and passing through the point $\mathrm{P}(3,4)$
Need to find: The equation of the hyperbola.
Let, the equation of the hyperbola be:
$\frac{x^{2}}{a^{2}}-\frac{y^{2}}{b^{2}}=1$
It passes through the point $P(3,4)$
So putting the values of $(x, y)$ we get,
$\frac{3^{2}}{a^{2}}-\frac{4^{2}}{b^{2}}=1 \Rightarrow \frac{9}{a^{2}}-\frac{16}{b^{2}}=1 \cdots(1)$
Foci at $(0, \pm \sqrt{14})$
So, ae $=\sqrt{14}$
We know, $e=\sqrt{1+\frac{b^{2}}{a^{2}}}$
$\Rightarrow a \sqrt{1+\frac{b^{2}}{a^{2}}}=\sqrt{14}$
$\Rightarrow \sqrt{a^{2}+b^{2}}=\sqrt{14}$
$\Rightarrow \mathrm{a}^{2}+\mathrm{b}^{2}=14$ [Squaring on both sides]
$\Rightarrow a^{2}=14-b^{2}$ .............(2)
Comparing (1) and (2) we get
$\frac{9}{14-b^{2}}-\frac{16}{b^{2}}=1$
$\frac{9}{14-b^{2}}=1+\frac{16}{b^{2}}=\frac{b^{2}+16}{b^{2}}$
$9 b^{2}=14 b^{2}-b^{4}+224-16 b^{2}$
$b^{4}+11 b^{2}-224=0$
Solving the equations we get,
$b_{1}=\sqrt{\frac{1}{2}(-11+3 \sqrt{113})}$
$b_{2}=-\sqrt{\frac{1}{2}(-11+3 \sqrt{113})}$
$b_{3}=(-i) \sqrt{\frac{1}{2}(11+3 \sqrt{113})}$
$b_{4}=i \sqrt{\frac{1}{2}(11+3 \sqrt{113})}$
With the help of any of these values of b we can't find out the equation of the hyperbola.
* This is the only process we can apply in this standard.