问题
通过凑微分,如何计算 [$\textcolor{Orange}{\int f(\cos x) \sin x \mathrm{d} x}$] ?选项
[A]. $\int$ $f(\cos x) \sin x$ $\mathrm{d} x$ $=$ $- \int$ $f(\cos x)$ $\mathrm{d} (\sin x)$[B]. $\int$ $f(\cos x) \sin x$ $\mathrm{d} x$ $=$ $\int$ $f(\cos x)$ $\mathrm{d} (\cos x)$
[C]. $\int$ $f(\cos x) \sin x$ $\mathrm{d} x$ $=$ $- \int$ $f(\cos x)$ $\mathrm{d} (\cos x)$
[D]. $\int$ $f(\cos x) \sin x$ $\mathrm{d} x$ $=$ $\int$ $f(\cos x)$ $\mathrm{d} (\sin x)$
$$\int \textcolor{Red}{f(\cos x)} \textcolor{Green}{\times} \textcolor{Red}{\sin x} \mathrm{d} \textcolor{Yellow}{x} =$$ $$\textcolor{Orange}{-} \int \textcolor{Red}{f(\cos x)} \mathrm{d} (\textcolor{Yellow}{\cos x}).$$