% Title: Demonstration sans parole : identite remarquable
% Author: Jacques Duma
% Site: http://math.et.info.free.fr/TikZ/index.html

\documentclass{article}

\usepackage{tikz}

\begin{document}

\pagestyle{empty}

\section*{Identit\'e remarquable}

\vfill

\begin{center}
\begin{tikzpicture} [scale=1.5,transform shape]
\fill[color=yellow!25] (2,2)rectangle(5,5);
\draw[thick,fill=blue!25] (0,0)rectangle(2,5);
\draw[thick,fill=blue!25] (0,5)rectangle(5,7);
\draw[thick,fill=blue!25] (2,0)rectangle(7,2);
\draw[thick,fill=blue!25] (5,2)rectangle(7,7);
\node[below] at (1,0){$b$};
\node[below] at (4.5,0){$a$};
\node[left] at (0,2.5){$a$};
\node[left] at (0,6){$b$};
\end{tikzpicture}
\end{center}

\vfill

{\huge $$(a+b)^2-(a-b)^2=4ab$$}

\vfill

\end{document}
