If $\cos ^{-1}\left(\frac{12}{13}\right)+\sin ^{-1}\left(\frac{3}{5}\right)=\sin ^{-1} P$, then the value of…

If $\cos ^{-1}\left(\frac{12}{13}\right)+\sin ^{-1}\left(\frac{3}{5}\right)=\sin ^{-1} P$, then the value of $P$ is
  1. $\frac{63}{65}$
  2. $\frac{56}{65}$
  3. $\frac{48}{65}$
  4. $\frac{36}{65}$

Solution

$\begin{aligned} & \sin ^{-1}\left(\frac{3}{5}\right)+\cos ^{-1}\left(\frac{12}{13}\right) \\ & =\sin ^{-1}\left(\frac{3}{5}\right)+\sin ^{-1} \sqrt{1-\left(\frac{12}{13}\right)^2} \\ & =\sin ^{-1}\left(\frac{3}{5}\right)+\sin ^{-1}\left(\frac{5}{13}\right) \\ & =\sin ^{-1}\left[\frac{3}{5} \sqrt{1-\left(\frac{5}{13}\right)^2}+\frac{5}{13} \sqrt{1-\left(\frac{3}{5}\right)^2}\right] \\ & =\sin ^{-1}\left(\frac{3}{5} \times \frac{12}{13}+\frac{5}{13} \times \frac{4}{5}\right) \\ & =\sin ^{-1}\left(\frac{56}{65}\right)\end{aligned}$ $\therefore \quad P=\frac{56}{65}$

Asked in: MHT CET 2024 (16 May Shift 2)

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