\documentclass[a3paper,oneside, landscape,12pt]{article}

\usepackage{geometry}
\usepackage{titlesec}
\usepackage[utf8]{inputenc} % un package
\usepackage[T1]{fontenc}      % un second package
\usepackage{lmodern}
\usepackage[francais]{babel}  % un troisième package
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{pstricks-add}

%\color{blue}
\geometry{margin={1in,1in}}
%\setlength{\unitlength}{1mm}
\renewcommand{\FrenchLabelItem}{\textbullet}
\titlespacing*{\chapter}{0pt}{-70pt}{20pt}
\titleformat{\chapter}[display]{\normalfont\huge\bfseries}{\chaptertitlename\ \thechapter}{20pt}{\Huge}

\begin{document}
\noindent
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$AB = \sqrt{(x_B-x_A)^2 + (y_B-y_A)^2} \leq r$\\
$\sqrt{(recordButtonCoordinates[0]*windowSize[0] - (float)mouseX)^2 + (recordButtonCoordinates[1]*windowSize[1] - (float)mouseY)^2} \hspace{2mm} \leq \hspace{2mm} buttonRadius*windowSize[0]$
\end{document}
