将下列恒等式放在右侧括号中，并赋予其编号 (*)

Question

我想要将以下恒等式放在右侧并赋予其编号 (*)

\begin{align*}
\mu(E)&=\sup\{\mu(K)~:~ K \text{ is a compact subset of } E \}\\
&=\inf\{\mu(U)~:~ U \text{ is an open set containing } E \}
\end{align*} 

我尝试这样做

\left \begin{align*}
\mu(E)&=\sup\{\mu(K)~:~ K \text{ is a compact subset of } E \}\\
&=\inf\{\mu(U)~:~ U \text{ is an open set containing } E \}
\end{align*}\right\}

但它显示错误。请帮帮我。

Answer 1

也许像下面这样，使用rcases环境（由包提供mathtools）：

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{equation}
\mu(E)=
\begin{rcases}
\sup\{\mu(K)\} \colon \text{$K$ is a compact subset of $E$}\\
\inf\{\mu(U)\} \colon \text{$U$ is an open set containing $E$}
\end{rcases}
\tag{$*$}
\end{equation} 
\end{document}