If the point $(1,1)$ and the origin lie in the same region with respect to the hyperbola…

If the point $(1,1)$ and the origin lie in the same region with respect to the hyperbola $\frac{x^2}{a^2}-\frac{y^2}{1}=1(a>0)$, then the range of a is
  1. $\left(\frac{1}{\sqrt{2}}, \infty\right)$
  2. $\left(0, \frac{1}{\sqrt{2}}\right)$
  3. $(0,1)$
  4. $(0, \sqrt{2})$

Solution

Since centre of given hyperbola is $(0,0)$ Given that origin and $(1,1)$ lie in same region therefore $(1,1)$ lie inside the hyperbola. $\begin{aligned} & \therefore \frac{1}{a^2}-1-1 < 0 \Rightarrow \frac{2 a^2-1}{a^2} < 0 \Rightarrow a>\frac{1}{\sqrt{2}} \\ & \therefore a \in\left(\frac{1}{\sqrt{2}}, \infty\right) \end{aligned}$

Asked in: AP EAMCET 2023 (17 May Shift 1)

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