1 câu trả lời
\[\begin{array}{l} y = \frac{{\sin x}}{{\cos x + 1}}\\ DK:\,\,\,\cos x + 1 \ne 0\\ \Leftrightarrow \cos x \ne - 1\\ \Leftrightarrow x \ne - \frac{\pi }{2} + k2\pi \,\,\,\left( {k \in Z} \right).\\ \Rightarrow D = R\backslash \left\{ { - \frac{\pi }{2} + k2\pi \,\,\left( {k \in Z} \right)} \right\}. \end{array}\]
