Let $x \in(0,1)$. The set of all $x$ such that $\sin ^{-1} x>\cos ^{-1} x$, is the interval:

Let $x \in(0,1)$. The set of all $x$ such that $\sin ^{-1} x>\cos ^{-1} x$, is the interval:
  1. $\left(\frac{1}{2}, \frac{1}{\sqrt{2}}\right)$
  2. $\left(\frac{1}{\sqrt{2}}, 1\right)$
  3. $(0,1)$
  4. $\left(0, \frac{\sqrt{3}}{2}\right)$

Solution

Given $\sin ^{-1} x>\cos ^{-1} x$ where $x \in(0,1)$ $ \begin{aligned} &\Rightarrow \sin ^{-1} x>\frac{\pi}{2}-\sin ^{-1} x \\ &\Rightarrow 2 \sin ^{-1} x>\frac{\pi}{2} \Rightarrow \sin ^{-1} x>\frac{\pi}{4} \\ &\Rightarrow x>\sin \frac{\pi}{4} \Rightarrow x>\frac{1}{\sqrt{2}} \end{aligned} $ Maximum value of $\sin ^{-1} x$ is $\frac{\pi}{2}$ So, maximum value of $x$ is 1 . So, $x \in\left(\frac{1}{\sqrt{2}}, 1\right)$

Asked in: JEE Main 2013 (25 Apr Online)

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