Find the equation of the hyperbola with eccentricity $\sqrt{2}$ and the distance between whose foci is 16.
Given: Eccentricity is $\sqrt{2}$, and the distance between foci is 16
Need to find: The equation of the hyperbola.
Let, the equation of the hyperbola be:
$\frac{x^{2}}{a^{2}}-\frac{y^{2}}{b^{2}}=1$
Distance between the foci is 16, i.e., $2 \mathrm{ae}=16$
And also given, the eccentricity, e =
$\sqrt{2}$
Therefore,
$2 \mathrm{a} \sqrt{2}=16$
$a=\frac{16}{2 \sqrt{2}}=\frac{8}{\sqrt{2}}=4 \sqrt{2} \cdots(1)$
We know that, $e=\sqrt{1+\frac{b^{2}}{a^{2}}}$
Therefore,
$\Rightarrow \sqrt{1+\frac{b^{2}}{a^{2}}}=\sqrt{2}$
$\Rightarrow 1+\frac{\mathrm{b}^{2}}{\mathrm{a}^{2}}=2$ [Squaring both sides]
$\Rightarrow \frac{\mathrm{b}^{2}}{\mathrm{a}^{2}}=1$
$\Rightarrow \mathrm{b}^{2}=\mathrm{a}^{2}=32[$ From (1) $]$
So, the equation of the hyperbola is,
$\frac{x^{2}}{a^{2}}-\frac{y^{2}}{b^{2}}=1 \Rightarrow \frac{x^{2}}{32}-\frac{y^{2}}{32}=1 \Rightarrow x^{2}-y^{2}=32$ [Answer]