latex的大括号_大括号和小括号的用法

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方法一：
$$ f(x)=\left\{ 
 \begin{ 
aligned} x & = & \cos(t) \\ y & = & \sin(t) \\ z & = & \frac xy \end{ 
aligned} \right. $$
方法二：
$$ F^{ 
HLLC}=\left\{ 
 \begin{ 
array}{ 
rcl} F_L & & { 
0 < S_L}\\ F^*_L & & { 
S_L \leq 0 < S_M}\\ F^*_R & & { 
S_M \leq 0 < S_R}\\ F_R & & { 
S_R \leq 0} \end{ 
array} \right. $$
方法三:
$$f(x)= \begin{ 
cases} 0& \text{ 
x=0}\\ 1& \text{ 
x!=0} \end{ 
cases}$$
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