Hàm số xác định khi:
\(\left\{{}\begin{matrix}cot2x-1\ne0\\sin2x\ne0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}cot2x\ne1\\sin2x\ne0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x\ne\dfrac{\pi}{4}+k\pi\\2x\ne k\pi\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ne\dfrac{\pi}{8}+\dfrac{k\pi}{2}\\x\ne\dfrac{k\pi}{2}\end{matrix}\right.\)




