If $\sin \left(\cot ^{-1}(x+1)\right)=\cos \left(\tan ^{-1} x\right)$, then the value of $x$ is equal to
If $\sin \left(\cot ^{-1}(x+1)\right)=\cos \left(\tan ^{-1} x\right)$, then the value of $x$ is equal to
- $-\frac{1}{2}$
- $-\frac{1}{3}$
- $\frac{1}{2}$
- $\frac{1}{3}$
Solution
$\begin{aligned} & \sin \left(\cot ^{-1}(x+1)\right)=\cos \left(\tan ^{-1} x\right) \\ & \Rightarrow \operatorname{sinsin}^{-1}\left\{\frac{1}{\sqrt{(x+1)^2+1}}\right\}=\operatorname{coscos}^{-1}\left\{\frac{1}{\sqrt{x^2+1}}\right\} \\ & \Rightarrow \sqrt{x^2+1}=\sqrt{x^2+2 x+2} \\ & \Rightarrow x=\frac{-1}{2}\end{aligned}$
Asked in: MHT CET 2022 (10 Aug Shift 2)
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