Latex测试代码

http://hwiechern.blog.163.com/blog/static/10679662201511293555279/

下面的这段代码应该显示为${\rm \LaTeX}$数学公式：$$\begin{align*} &\int{\frac{dx}{\sin x(1+\cos x)}}\\ &=\int{\frac{\sin xdx}{\sin^2 x(1+\cos x)}}\\ &=-\int{\frac{d\cos x}{(1-\cos^2 x)(1+\cos x)}}\\ &=-\int{\frac{d\cos x}{(1-\cos x)(1+\cos x)^2}}\\ &=-\int{\left(\frac{1}{4(1-u)}+\frac{1}{4(1+u)}+\frac{1}{2(1+u)^2}\right)du},u=\cos x\\ &=\frac{1}{4}\ln\frac{1-u}{1+u}+\frac{1}{2(1+u)}+C\\ &=\frac{1}{4}\ln\frac{1-\cos x}{1+\cos x}+\frac{1}{2(1+\cos x)}+C\\ &=\frac{1}{2}\ln(\tan\frac{x}{2})+\frac{1}{2(1+\cos x)}+C\\ \end{align*}$$