Q64 / 180 · KCET 2016 · Mathematics

The value of \( \sin ^{-1}\left(\cos \frac{53 \Pi}{5}\right) \) is

  • A
    \( 3 \frac{\Pi}{5} \)
  • B
    \(-3 \frac{\Pi}{5} \)
  • C
    \( \frac{\Pi}{10} \)
  • Correct answer
    D
    \( -\frac{\Pi}{10} \)

Solution

Given that, \( \sin ^{-1}\left(\cos \frac{53 \pi}{5}\right) \) \( =\sin ^{-1}\left\{\cos \left(10 \Pi+\frac{3 \pi}{5}\right)\right\} \) \( =\sin ^{-1}\left(\cos \frac{3 \pi}{5}\right) \) \( =\sin ^{-1}\left(\cos \left(\frac{\Pi}{2}+\frac{\Pi}{10}\right)\right) \) \( =\sin ^{-1}\left(-\sin \left(\frac{\Pi}{10}\right)\right) \) \( =\sin ^{-1}\left(\sin \left(-\frac{\Pi}{10}\right)\right)=\frac{-\Pi}{10} \)

Hence, the correct answer is option: 'D'.

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