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\begin{document}
\chapter{فصل}
\section{بخش}
%\baselineskip=.95cm
\begin{defi}[اعداد مختلط]%
{1.1}
این یک تعریف است. 
\begin{align}
(a+bi) & = (a+c), \nonumber \\
(a+bi) & = (ac - bd) , 
\end{align}
\end{defi}
\begin{align} \label{eq:2}
a & = b \nonumber \\
b & = c \nonumber \\
d & = z 
\end{align}
\begin{defi}[معادلات]
{1.2}
طبق معادله 
\eqref{eq:2} 
داریم 
\begin{align} \label{eq:3}
a = b 
\end{align}
\end{defi}

\end{document}