Answer
This does not make sense.
Work Step by Step
Please note that the identity $\sin ^{-1}(\sin x)=x$ holds only for $x \in [-\frac{\pi }{2}, \frac{\pi }{2}]$. But, $\frac{5\pi }{4} \not \in [-\frac{\pi }{2}, \frac{\pi }{2}]$. (In fact, $\frac{5 \pi }{4}$ lies outside of the range of the function $\sin ^{-1}$, $[-\frac{\pi }{2}, \frac{\pi }{2}]$.)
