ĐKXĐ: \(\left\{{}\begin{matrix}2x< >\dfrac{\Pi}{2}+k\Pi\\\sin2x< >-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ne\dfrac{\Pi}{4}+\dfrac{k\Pi}{2}\\2x\ne-\dfrac{\Pi}{2}+k2\Pi\end{matrix}\right.\Leftrightarrow x\notin\left\{\dfrac{\Pi}{4}+\dfrac{k\Pi}{2};-\dfrac{\Pi}{4}+k\Pi\right\}\)