Solve the Following Questions

Question:

$2 \pi-\left(\sin ^{-1} \frac{4}{5}+\sin ^{-1} \frac{5}{13}+\sin ^{-1} \frac{16}{65}\right)$ is equal to:

  1. $\frac{7 \pi}{4}$

  2. $\frac{5 \pi}{4}$

  3. $\frac{3 \pi}{2}$

  4. $\frac{\pi}{2}$


Correct Option: , 3

Solution:

$2 \pi-\left(\sin ^{-1}\left(\frac{4}{5}\right)+\sin ^{-1}\left(\frac{5}{13}\right)+\sin ^{-1}\left(\frac{16}{65}\right)\right)$

$=2 \pi-\left(\tan ^{-1}\left(\frac{4}{3}\right)+\tan ^{-1}\left(\frac{5}{12}\right)+\tan ^{-1}\left(\frac{16}{63}\right)\right)$

$=2 \pi-\left(\tan ^{-1}\left(\frac{63}{16}\right)+\tan ^{-1}\left(\frac{16}{63}\right)\right)$

$=2 \pi-\frac{\pi}{2}=\frac{3 \pi}{2}$

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