% Exercise 6.3, first part
\documentclass{standalone}

\usepackage{tikz}
\usetikzlibrary{calc}

\begin{document}
\begin{tikzpicture}[x=1cm,y=1cm]
  % clip output to the given rectangle
  \clip (1,1) rectangle +(6,6);
  % loop (with loop variable \j)
  \foreach \j in {0,...,3} {%
    % draw a circle of radius 1 whose centre is at the given coordinate
    \draw (2*\j,1) circle (1);
    % coordinates can be added as follows: ($(\j,0) + (1,1)$)

    % todo: complete this example!
  }
\end{tikzpicture}
\end{document}
