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TS EAMCET · Maths · Trigonometric Ratios & Identities

If \(\cosh ^{-1} x=2 \log _e(\sqrt{2}+1)\), then \(x=\)

  1. A 1
  2. B 2
  3. C 4
  4. D 3
Verified Solution

Answer & Solution

Correct Answer

(D) 3

Step-by-step Solution

Detailed explanation

We have, \(\cosh ^{-1} x=2 \log _e(\sqrt{2}+1)\) \[ \begin{aligned} & \Rightarrow \log _e\left(x+\sqrt{x^2-1}\right)=\log _e(\sqrt{2}+1)^2 \\ & \Rightarrow \quad x+\sqrt{x^2-1}=(\sqrt{2}+1)^2 \\ & \Rightarrow \quad x+\sqrt{x^2-1}=3+2 \sqrt{2}=3+\sqrt{8} \end{aligned} \] On…