ho risolto così
`
\documentclass{article}
\usepackage{subcaption}
\usepackage{graphicx}
\usepackage{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}
\begin{figure}
\rotatebox{90}{
\begin{minipage}{.4\linewidth}
\centering\includestandalone[width=5cm]{divpolinomi7}
\subcaption{Sette}\label{fig:1g}
\end{minipage}%
}\qquad
\rotatebox{90}{
\begin{minipage}{.4\linewidth}
\centering\includestandalone[width=5cm]{divpolinomi6}
\subcaption{Sei}\label{fig:1f}
\end{minipage}%
}\qquad
\rotatebox{90}{
\begin{minipage}{.4\linewidth}
\centering\includestandalone[width=5cm]{divpolinomi5}
\subcaption{Cinque}\label{fig:1e}
\end{minipage}%
}\qquad
\rotatebox{90}{
\begin{minipage}{.4\linewidth}
\centering\includestandalone[width=5cm]{divpolinomi4}
\subcaption{Quattro}\label{fig:1d}
\end{minipage}%
}\qquad
\rotatebox{90}{
\begin{minipage}{.4\linewidth}
\centering\includestandalone[width=5cm]{divpolinomi3}
\subcaption{Tre}\label{fig:1c}
\end{minipage}
}\qquad
\rotatebox{90}{
\begin{minipage}{.4\linewidth}
\centering\includestandalone[width=5cm]{divpolinomi2}
\subcaption{Due}\label{fig:1b}
\end{minipage}
}\qquad
\rotatebox{90}{
\begin{minipage}{.4\linewidth}
\centering\includestandalone[width=5cm]{divpolinomi1}
\subcaption{Uno}\label{fig:1a}
\end{minipage}%
}\qquad
\caption{Divisione fra polinomi}\label{fig:1}
\end{figure}
\end{document}
`
Sicuramente è migliorabile
saluti
claudio