\documentclass[12pt,a4paper]{article}

\usepackage{lipsum}
\usepackage{amsmath,amssymb, amsthm,amsopn}

\usepackage[OT1,OT2]{fontenc}
\newcommand{\latinicom}[1]{\fontencoding{OT1}\selectfont{#1}\fontencoding{OT2}\selectfont}
\newcommand{\cirilicom}[1]{\fontencoding{OT2}\selectfont{#1}\fontencoding{OT1}\selectfont}

\theoremstyle{plain}
\newtheorem{teorema}{Teorema}[section]
\newtheorem{posledica}{Posledica}[section]
\newtheorem{lema}{Lema}[section]

\theoremstyle{definition}
\newtheorem{definicija}{Definicija}[section]
\newtheorem{primer}{Primer}[section]
\renewcommand{\proofname}{\textbf{Dokaz}}
\renewcommand{\qed}{\hfill$\blacksquare$}

\DeclareMathOperator{\tg}{tg}
\DeclareMathOperator{\ctg}{ctg}

\begin{document}

\section{Pitagorina teorema}
\begin{teorema}[Pitagorin teorema] \label{pitagora}
  Ako je trougao $ABC$ pravougli sa pravim uglom kod temena $C$, onda je 
  \begin{equation}\label{jednacina1}
  AC^2+BC^2 = AC^2.
  \end{equation}
\end{teorema}
\begin{proof}
  ....
\end{proof}
\begin{definicija}
  Prva definicija
\end{definicija}
\begin{teorema}[Pitagorin teorema]
  Ako je trougao $ABC$ pravougli sa pravim uglom kod temena $C$, onda je $AC^2+BC^2 = AC^2$.
\end{teorema}
\section{C1irilichni tekst}
\begin{primer}
  Prvi primer
\end{primer}
\begin{definicija}
  Druga definicija
\end{definicija}
Iz teoreme \ref{pitagora} sledi ...
Iz jednachine \eqref{jednacina1} sledi ...

\lipsum[2]
\Large{dj zh lj nj c1 ch d2 sh} \\

\Large{Dj Zh Lj Nj C1 Ch D2 Sh} \\
kon{}junkcija\\
kon$ $junkcija \\
t$ $s

\begin{align*}
3x+2y &= 7, \nonumber\\
-2x + y -3z &= 17.
\end{align*}

\begin{equation}
\begin{aligned}
3x+2y &= 7,\\
-2x + y -3z &= 17.
\end{aligned}
\end{equation}

\begin{align}
&X+Y - \nonumber \\
&Z = W.
\end{align}

\begin{align}
\sin^2 x + \cos^2 x &= 1, \\
\tg x \ctg x &=1\\
\sum_{i=1}^{n} i^2 &= \frac {1}{6} n(n+1)(2n+1) \\
\int\limits_0^{+\infty} f(x) \mathrm{d}x \\
\int_0^{+\infty} f(x) \mathrm{d}x
%%%
\end{align}

$\displaystyle \prod_{i=1}^{n} x_i$ tekst \\
 $\mathbb{N} \subset \mathbb{Z} \subset \mathbb{Q} \subset \mathbb{R} \subset \mathbb{C}$
 
 $$\left(
     \begin{array}{ccc}
       a_{11} & a_{12} & a_{13} \\
       a_{21} & a_{22} & a_{23} \\
       a_{31} & a_{32} & a_{33} \\
     \end{array}
   \right)
 $$
\end{document}



















\usepackage{lipsum}

\lipsum[2]

konjunkcija \v z

\cirilicom{\v z}





\theoremstyle{plain}
\newtheorem{teorema}{Teorema}[section]
\newtheorem{posledica}{Posledica}[section]
\newtheorem{lema}{Lema}[section]

\theoremstyle{definition}
\newtheorem{definicija}{Definicija}[section]
\newtheorem{primer}{Primer}[section]
\renewcommand{\proofname}{\textbf{Dokaz}}
\renewcommand{\qed}{\hfill$\blacksquare$}


