MCQ
$\sin \left[3 \sin ^{-1}\left(\frac{1}{5}\right)\right]=$
  • $\frac{71}{125}$
  • B
    $\frac{74}{125}$
  • C
    $\frac{3}{5}$
  • D
    $\frac{1}{2}$

Answer

Correct option: A.
$\frac{71}{125}$
(A) $\sin \left[3 \sin ^{-1}\left(\frac{1}{5}\right)\right]=\sin \left[\sin ^{-1}\left\{3\left(\frac{1}{5}\right)-4\left(\frac{1}{5}\right)^3\right\}\right]$
$=\sin \left[\sin ^{-1}\left\{\frac{3}{5}-\frac{4}{125}\right\}\right]=\sin \left[\sin ^{-1}\left(\frac{75-4}{125}\right)\right]$
$=\sin \left[\sin ^{-1} \frac{71}{125}\right]=\frac{71}{125}$

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