\documentclass[11pt,a4paper,oneside]{article}

\usepackage[T2A]{fontenc}
\usepackage[russian]{babel}
\usepackage[utf8]{inputenc}
\usepackage{amsmath,amssymb}

% Делаем лист нужного размера
\textwidth=192mm
\textheight=272mm
\hoffset=-35mm
\voffset=-35mm

\renewcommand{\t}{\texttt}    % моноширинный текст
\renewcommand{\le}{\leqslant}
\renewcommand{\ge}{\geqslant}

\def\SO{\Rightarrow}         % =>
\def\EQ{\Leftrightarrow}     % <=>
\newcommand{\q}[1]{\langle #1 \rangle} % <x>

\begin{document}

\begin{center}
Разные Математические значки: \\
$\t{Пример:} \q{a} \le b \ge c \SO x \EQ y$ 
\end{center}

$$
 \pm                  \cap                \diamond                    \oplus      
 \mp                  \cup                \bigtriangleup              \ominus     
 \times               \uplus              \bigtriangledown            \otimes     
 \div                 \sqcap              \triangleleft               \oslash     
 \ast                 \sqcup              \triangleright              \odot       
 \star                \vee                \lhd^b                    \bigcirc    
 \circ                \wedge              \rhd^b                    \dagger     
 \bullet              \setminus           \unlhd^b                  \ddagger    
 \cdot                \wr                 \unrhd^b                  \amalg      
$$

$$
 \leq                 \geq                \equiv              \models       
 \prec                \succ               \sim                \perp         
 \preceq              \succeq             \simeq              \mid          
 \ll                  \gg                 \asymp              \parallel     
 \subset              \supset             \approx             \bowtie       
 \subseteq            \supseteq           \cong               \Join^b
 \sqsubset^b        \sqsupset^b       \neq                \smile        
 \sqsubseteq          \sqsupseteq         \doteq              \frown        
 \in                  \ni                 \propto             =             
 \vdash               \dashv              <                   >             
$$

$$
 \ldots               \cdots              \vdots              \ddots        
 \aleph               \prime              \forall             \infty        
 \hbar                \emptyset           \exists             \Box^b      
 \imath               \nabla              \neg                \Diamond^b  
 \jmath               \surd               \flat               \triangle     
 \ell                 \top                \natural            \clubsuit     
 \wp                  \bot                \sharp              \diamondsuit  
 \Re                  \|                  \backslash          \heartsuit    
 \Im                  \angle              \partial            \spadesuit    
 \mho^b             .                   |
$$

\end{document}