公式格式

Question

我需要以以下格式显示 3 个方程式：

我得到的是

代码如下

\documentclass{report}
\usepackage{amsmath}

\begin{document}
\begin{equation}\label{Equ.3.3}
V'=e^{(ja)}\times V
\end{equation}

\begin{equation}\label{Equ.3.4}
=[\cos(a) + j \times \sin(a)] \times (x+j \times y)
\end{equation}

\begin{equation}\label{Equ.3.5}
=x \cdot \cos(a) - y\cdot \sin(a) + j \cdot [x \cdot \sin(a) + y \cdot     \cos(a)]
\end{equation}


\end{document}

请您建议如何实现预期结果。

Answer 1

您可以像下面这样使用对齐环境。& 字符为对齐环境放置一个对齐垂直锚点。

\documentclass{report}
\usepackage{amsmath}

\begin{document}
Each step of the expression can be referenced easily~\eqref{Equ.3.3},~\eqref{Equ.3.4} and~\eqref{Equ.3.5}.
\begin{align}
V' &=e^{(ja)}\times V \label{Equ.3.3}\\
&=[\cos(a) + j \times \sin(a)] \times (x+j \times y) \label{Equ.3.4}\\
&=x \cdot \cos(a) - y\cdot \sin(a) + j \cdot [x \cdot \sin(a) + y \cdot     \cos(a)] \label{Equ.3.5}
\end{align}
But I would say that usually one just labels the final result~\eqref{Equ.3}.
\begin{align}
V' &=e^{(ja)}\times V \nonumber\\
&=[\cos(a) + j \times \sin(a)] \times (x+j \times y) \nonumber\\
&=x \cdot \cos(a) - y\cdot \sin(a) + j \cdot [x \cdot \sin(a) + y \cdot     \cos(a)] \label{Equ.3}
\end{align}
Likewise, in a single-line environment we can achieve the same~\eqref{Equ.3b}. In this case though, the label is at the mid-height of the aligned box by default.
\begin{equation}
\begin{aligned}
V' &=e^{(ja)}\times V \\
&=[\cos(a) + j \times \sin(a)] \times (x+j \times y) \\
&=x \cdot \cos(a) - y\cdot \sin(a) + j \cdot [x \cdot \sin(a) + y \cdot     \cos(a)]
\end{aligned}
\label{Equ.3b}
\end{equation}

\end{document}