% This picture represents the fact that rotations are rigid motions
% (C) Thiago Brevidelli
\begin{tikzpicture}[scale=1.25]
  % The axis
  \draw (-1, 0) -- (1, 0) (0, -1) -- (0, 1);

  % The right square
  \draw (-.5, .5) -- ++(1, 0) -- ++(0, -1) -- ++(-1, 0) -- cycle;

  % The rotated square
  \begin{scope}[rotate=-45]
    \draw (-.5, .5) -- ++(1, 0) -- ++(0, -1) -- ++(-1, 0) -- cycle;
  \end{scope}

  % The rotation
  \draw[->] (90:.75) ++(.25, .25) arc (90:0:.75);
\end{tikzpicture}
