Question
Write the value of $\cos\big(\sin^{-1}\text{x}+\cos^{-1}\text{x}\big),|\text{x}|\leq1$

Answer

We have$|\text{x}|\leq1$
$\Rightarrow\pm\text{x}\leq1$
$\Rightarrow\text{x}\leq1$ or $\Rightarrow-\text{x}\leq1$
$\Rightarrow\text{x}\leq1$ or $\Rightarrow\text{x}\geq1$
$\Rightarrow\in[-1, 1]$
Now,
$\cos\big(\sin^{-1}\text{x}+\cos^{-1}\text{x}\big)=\cos\Big(\frac{\pi}{2}\Big)$ $\Big[\because\ \sin^{-1} \text{x}+\cos^{-1}\text{x}=\frac{\pi}{2}\Big]$
$=0$

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