If $f(x)=\left | \sin x \right |$, then domain of $f$ for the existence of inverse is
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$[0,\pi ]$
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$\left [ 0,\dfrac{\pi }{2} \right ]$
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$\left [ -\dfrac{\pi }{4},\dfrac{\pi }{4} \right ]$
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$\left [ -\dfrac{\pi }{2},\dfrac{\pi }{2} \right ]$
Reveal answer
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B
Correct answer
Explanation
We know that $-1 \leq \sin x \leq 1$ for $x \in \left [ -\dfrac{\pi}{2}, \dfrac{\pi}{2} \right] $.
For $| \sin x |$ to be invertible, the function has to be one-to-one.
Thus, we need unique values of $x$ that give unique values of $f$ and vice versa.
For $x \in \left [0, \dfrac{\pi}{2} \right]$, $0 \leq \sin x \leq 1 \Rightarrow 0 \leq | \sin x \leq 1$
For $x \in \left [-\dfrac{\pi}{2},0 \right]$, $-1 \leq \sin x \leq 0 \Rightarrow 0 \leq | \sin x \leq 1$.So, we have
$ \left [0, \dfrac{\pi}{2} \right] \rightarrow\left [0, 1 \right]$
$ \left [- \dfrac{\pi}{2},0 \right] \rightarrow\left [0, 1 \right]$$ \left [0, \dfrac{\pi}{2} \right] \rightarrow\left [0, 1 \right]$
Since both the domains of $|\sin x|$ map to$\left [0, 1 \right]$, we consider only one of them for $x$ to be unique.
Here, according to the options, the domain of $f$ must be$\left [0, \dfrac{\pi}{2} \right]$.