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AP EAMCET · Maths · Inverse Trigonometric Functions

\(\operatorname{Sech}^{-1}(\sin \alpha)=\)

  1. A \(\log \left(\sin \alpha+\sqrt{\sin ^2 \alpha-1}\right)\)
  2. B \(\log (\tan \alpha+1)\)
  3. C \(\log \left(\cot \frac{\alpha}{2}\right)\)
  4. D \(\log \left(\frac{1+\tan \alpha}{2 \sin \alpha}\right)\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\log \left(\cot \frac{\alpha}{2}\right)\)

Step-by-step Solution

Detailed explanation

\(\operatorname{Sech}^{-1}(\sin \alpha) = \log \left(\frac{1+\sqrt{1-\sin^2 \alpha}}{\sin \alpha}\right)\) \(= \log \left(\frac{1+\cos \alpha}{\sin \alpha}\right)\) \(= \log \left(\frac{2\cos^2 \frac{\alpha}{2}}{2\sin \frac{\alpha}{2}\cos \frac{\alpha}{2}}\right)\)…