问题
[$\textcolor{Orange}{\int (\csc x \times \cot x) \mathrm{d} x}$] 的积分该怎么计算？选项
[A]. $\int$ $(\csc x \cot x)$ $\mathrm{d} x$ $=$ $\sec x$ $+$ $C$[B]. $\int$ $(\csc x \cot x)$ $\mathrm{d} x$ $=$ $\csc x$ $+$ $C$
[C]. $\int$ $(\csc x \cot x)$ $\mathrm{d} x$ $=$ $\csc x$
[D]. $\int$ $(\csc x \cot x)$ $\mathrm{d} x$ $=$ $- \csc x$ $+$ $C$
$$\int \textcolor{Red}{(\csc x \times \cot x)} \mathrm{d} x =$$ $$\int \textcolor{Red}{(\frac{1}{\sin x} \times \frac{\cos x}{\sin x})} \mathrm{d} x =$$ $$\textcolor{Red}{- \csc x} + \textcolor{Yellow}{C} =$$ $$\textcolor{Red}{\frac{- 1}{\sin x}} + \textcolor{Yellow}{C}.$$