The value of \(x\) that satisfies the equation \(\int_{\sqrt{2}}^x \frac{d t}{| t|…

The value of \(x\) that satisfies the equation \(\int_{\sqrt{2}}^x \frac{d t}{| t| \sqrt{t^2-1}}=\frac{\pi}{12}\) is
  1. 1
  2. 0
  3. \(-\sqrt{2}\)
  4. 2

Solution

$\begin{aligned} & \int_{\sqrt{2}}^x \frac{d t}{|t| \sqrt{t^2-1}}=\frac{\pi}{12} \\ & \Rightarrow \quad\left[\sec ^{-1} t\right]_{\sqrt{2}}^x=\frac{\pi}{12} \Rightarrow \sec ^{-1} x-\sec ^{-1} \sqrt{2}=\frac{\pi}{12} \\ & \Rightarrow \quad \sec ^{-1} x=\frac{\pi}{12}+\frac{\pi}{4}=\frac{\pi}{3} \\ & \Rightarrow \quad x=\sec \left(\frac{\pi}{3}\right)=2 \end{aligned}$

Asked in: AP EAMCET 2020 (17 Sep Shift 1)

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