\documentclass[14pt]{extreport}
\usepackage{amsthm,amssymb,amsmath,mathtools}
\usepackage{graphicx,caption,subcaption}
\usepackage{breqn}
\setkeys{breqn}{breakdepth={1}}
\usepackage{hyperref}[2010/09/11]
\newtheorem{definition}{تعریف}[section]
\newtheorem{theorem}{قضیه}[section]
\newtheorem{lemma}{لم}[section]
\newtheorem{proposition}{گزاره}[section]
\newtheorem{corollary}{نتیجه}[section]
\newtheorem{remark}{ملاحظه}[section]
\allowdisplaybreaks
\newcommand{\no}{\nonumber}
\usepackage[localise]{xepersian}
\settextfont{XB Zar}
\setdigitfont{Persian Modern}

\begin{document}

\begin{dmath}
\sin ( E )  ( -\sin
 ( \psi ( t )  )  ( {\frac {\rm d}{{\rm d}t
}}\psi ( t )  ) \cos ( E ) x_{25}-\sin
 ( \psi ( t )  )  ( {\frac {\rm d}{{\rm d}t
}}\psi ( t )  ) \sin ( E ) y_{25}-\cos
 ( \psi ( t )  )  ( {\frac {\rm d}{{\rm d}t
}}\psi ( t )  ) z_{25} )  ) +m ( 
 ( {\frac {{\rm d}^{2}}{{\rm d}{t}^{2}}}\psi ( t ) 
 ) z_{5}-\sin ( E )  ( {\frac {{\rm d}^{2}}{
{\rm d}{t}^{2}}}\theta ( t )  )  ( \sin ( 
\psi ( t )  ) \cos ( E ) x_{25}+\sin
 ( \psi ( t )  ) \sin ( E ) y_{25}+
\cos ( \psi ( t )  ) z_{25}+z_{5} ) -\sin
 ( E )  ( {\frac {\rm d}{{\rm d}t}}\theta ( t
 )  )  ( \cos ( \psi ( t )  ) 
 ( {\frac {\rm d}{{\rm d}t}}\psi ( t )  ) \cos
 ( E ) x_{25}+\cos ( \psi ( t )  ) 
 ( {\frac {\rm d}{{\rm d}t}}\psi ( t )  ) \sin
 ( E ) y_{25}-\sin ( \psi ( t )  ) 
 ( {\frac {\rm d}{{\rm d}t}}\psi ( t )  ) z_{25}
 ) -\cos ( \psi ( t )  )  ( {\frac 
{\rm d}{{\rm d}t}}\psi ( t )  ) \cos ( E
 )  ( {\frac {\rm d}{{\rm d}t}}\theta ( t ) 
 )  ( -\sin ( E ) x_{25}+\cos ( E ) y
_{25}+z_{25}+y_{5} ) -\sin ( \psi ( t ) 
 ) \cos ( E )  ( {\frac {{\rm d}^{2}}{{\rm d}{t}
^{2}}}\theta ( t )  )  ( -\sin ( E ) 
x_{25}+\cos ( E ) y_{25}+z_{25}+y_{5} )  ) 
 ( -\sin ( E )  ( \sin ( \psi ( t
 )  ) \cos ( E ) x_{25}+\sin ( \psi
 ( t )  ) \sin ( E ) y_{25}+\cos ( 
\psi ( t )  ) z_{25}+z_{5} ) -\sin ( \psi
 ( t )  ) \cos ( E )  ( -\sin ( 
E ) x_{25}+\cos ( E ) y_{25}+z_{25}+y_{5} ) 
 ) + ( m\cos ( E ) \cos ( \theta ( t
 )  ) -m\sin ( \theta ( t )  ) 
 ) g_{z}\, ( -\sin ( E ) x_{25}+\cos ( E
 ) y_{25}+z_{25}+y_{5} ) + ( m\sin ( \psi
 ( t )  ) \sin ( E ) \cos ( \theta
 ( t )  ) -m\cos ( \psi ( t ) 
 ) \sin ( \theta ( t )  )  ) g_{z}\,
 ( \sin ( \psi ( t )  ) \cos ( E
 ) x_{25}+\sin ( \psi ( t )  ) \sin
 ( E ) y_{25}+\cos ( \psi ( t )  ) z_
{25}+z_{5} ) + ( m\cos ( \psi ( t ) 
 ) \sin ( E ) \cos ( \theta ( t ) 
 ) +m\sin ( \psi ( t )  ) \sin ( 
\theta ( t )  )  ) g_{z}\, ( \cos ( 
\psi ( t )  ) \cos ( E ) x_{25}+\cos
 ( \psi ( t )  ) \sin ( E ) y_{25}-
\sin ( \psi ( t )  ) z_{25}+x_{5} ) -M\cos
 ( \theta ( t )  ) g_{z}\,y_{2}+M\sin ( 
\theta ( t )  ) g_{z}\,z_{2}- ( 1/2\,\cos
 ( \psi ( t )  ) \cos ( E )  ( {
\frac {\rm d}{{\rm d}t}}\theta ( t )  ) j_{x}+
 ( -1/2\,\sin ( E ) {\frac {\rm d}{{\rm d}t}}\theta
 ( t ) +1/2\,{\frac {\rm d}{{\rm d}t}}\psi ( t
 )  ) j_{{\it xy}}+1/2\,\sin ( \psi ( t ) 
 ) \cos ( E )  ( {\frac {\rm d}{{\rm d}t}}\theta
 ( t )  ) j_{{\it xz}} ) \sin ( \psi
 ( t )  )  ( {\frac {\rm d}{{\rm d}t}}\psi
 ( t )  ) \cos ( E ) + ( -1/2\,\sin
 ( \psi ( t )  )  ( {\frac {\rm d}{{\rm d}t
}}\psi ( t )  ) \cos ( E ) j_{{\it xz}}+1/
2\,\cos ( \psi ( t )  )  ( {\frac {\rm d}{
{\rm d}t}}\psi ( t )  ) \cos ( E ) j_{z}
 ) \sin ( \psi ( t )  ) \cos ( E
 ) {\frac {\rm d}{{\rm d}t}}\theta ( t ) + ( 1/2
\,\cos ( \psi ( t )  ) \cos ( E ) j_{
{\it xz}}-1/2\,\sin ( E ) j_{{\it yz}}+1/2\,\sin ( 
\psi ( t )  ) \cos ( E ) j_{z} ) 
\sin ( \psi ( t )  ) \cos ( E ) {
\frac {{\rm d}^{2}}{{\rm d}{t}^{2}}}\theta ( t ) + ( 1
/2\,\cos ( \psi ( t )  ) \cos ( E ) 
 ( {\frac {\rm d}{{\rm d}t}}\theta ( t )  ) j_{{
\it xz}}+ ( -1/2\,\sin ( E ) {\frac {\rm d}{{\rm d}t}}
\theta ( t ) +1/2\,{\frac {\rm d}{{\rm d}t}}\psi ( t
 )  ) j_{{\it yz}}+1/2\,\sin ( \psi ( t ) 
 ) \cos ( E )  ( {\frac {\rm d}{{\rm d}t}}\theta
 ( t )  ) j_{z} ) \cos ( \psi ( t
 )  )  ( {\frac {\rm d}{{\rm d}t}}\psi ( t
 )  ) \cos ( E ) + ( -1/2\,\sin ( 
\psi ( t )  )  ( {\frac {\rm d}{{\rm d}t}}\psi
 ( t )  ) \cos ( E ) j_{x}+1/2\,\cos
 ( \psi ( t )  )  ( {\frac {\rm d}{{\rm d}t
}}\psi ( t )  ) \cos ( E ) j_{{\it xz}}
 ) \cos ( \psi ( t )  ) \cos ( E
 ) {\frac {\rm d}{{\rm d}t}}\theta ( t ) + ( 1/2
\,\cos ( \psi ( t )  ) \cos ( E ) j_{
x}-1/2\,\sin ( E ) j_{{\it xy}}+1/2\,\sin ( \psi
 ( t )  ) \cos ( E ) j_{{\it xz}} ) 
\cos ( \psi ( t )  ) \cos ( E ) {
\frac {{\rm d}^{2}}{{\rm d}{t}^{2}}}\theta ( t )
1/2\,\sin ( \psi ( t ) 
 ) \cos ( E )  ( {\frac {\rm d}{{\rm d}t}}\theta
 ( t )  ) j_{z} ) \cos ( \psi ( t
 )  )  ( {\frac {\rm d}{{\rm d}t}}\psi ( t
 )  ) \cos ( E )
 1/2\,\sin ( \psi ( t ) 
 ) \cos ( E )  ( {\frac {\rm d}{{\rm d}t}}\theta
 ( t )  ) j_{z} ) \cos ( \psi ( t
 )  )  ( {\frac {\rm d}{{\rm d}t}}\psi ( t
 )  ) \cos ( E )
\end{dmath}

\end{document}