Find the equation of the hyperbola whose vertices are (±2, 0) and the eccentricity is 2.
Given: Vertices are (±2, 0) and the eccentricity is 2
Need to find: The equation of the hyperbola.
Let, the equation of the hyperbola be:
$\frac{x^{2}}{a^{2}}-\frac{y^{2}}{b^{2}}=1$
Vertices are $(\pm 2,0)$, that means, $a=2$
And also given, the eccentricity, $e=2$
We know that, $e=\sqrt{1+\frac{b^{2}}{a^{2}}}$
Therefore,
$\Rightarrow \sqrt{1+\frac{b^{2}}{a^{2}}}=2$
$\Rightarrow 1+\frac{\mathrm{b}^{2}}{\mathrm{a}^{2}}=4$ [Squaring both sides]
$\Rightarrow \frac{\mathrm{b}^{2}}{\mathrm{a}^{2}}=3$
$\Rightarrow \mathrm{b}^{2}=3 \mathrm{a}^{2}=3 \times 4=12[$ As $\mathrm{a}=2]$
So, the equation of the hyperbola is,
$\frac{x^{2}}{a^{2}}-\frac{y^{2}}{b^{2}}=1 \Rightarrow \frac{x^{2}}{4}-\frac{y^{2}}{12}=1[$ Answer $]$