\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{lipsum}
\usepackage{graphicx}
	\graphicspath{{img/}}
\begin{document}
\lipsum
\begin{center}
\includegraphics{avatar.eps}
\end{center}
\lipsum
\begin{center}
\includegraphics{nsi.eps}
\end{center}
\lipsum
\begin{center}
\includegraphics{sept.eps}
\end{center}
\lipsum
\begin{center}
\includegraphics[width=0.75\linewidth]{tangente.eps}
\end{center}
\end{document}