答案1
这是一个起点。
\documentclass{article}
\usepackage{amsmath}
% Important: Have a look at https://tex.meta.stackexchange.com/questions/228/.
\begin{document}
\begin{equation}
\sin x + m \cdot \cos y + t \tan x = 1
\label{eq:NiceEquation}
\end{equation}
I need to show the equation, \eqref{eq:NiceEquation}, in the following order.
\begin{align}
&+ m \cdot \cos y\\
&+ m \cdot \cos y + z \tan x = 1
\end{align}
\end{document}