\documentclass[12pt]{article}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[francais]{babel}
\usepackage{lmodern}
\usepackage[colorlinks=true,urlcolor=blue!50!black, linkcolor=blue!50!black]{hyperref}
\usepackage{pas-cours}
\usepackage[tikz]{bclogo}
\usepackage{mathrsfs}
\usepackage{tkz-euclide}
\usetikzlibrary{decorations.pathmorphing}
\usepackage{pas-math}
\usepackage[vmargin=1.5cm,rmargin=2cm,lmargin=1.5cm]{geometry}
\begin{document}
\chap[num=A,color=blue]{Construction d'une ellipse par affinité}{Stéphane PASQUET, \today, \url{http://www.mathweb.fr}}

\itemclass{blue}
\begin{bclogo}[%
	couleur=blue!20,%
	couleurBord=blue!50!black,%
	arrondi=0.1,%
	logo=\bcquestion,%
	ombre=true,%
	couleurOmbre=blue!50!black!50,%
	blur,%
	barre=snake]{Intér\^ets des activités}
\begin{enumerate}
\item Tracé de cercles
\item Tracé d'angles
\item Tracé de droites parallèles
\item Programme de construction
\end{enumerate}
\end{bclogo}

\bigskip

\begin{pasbox}[degrade,style=act]
\emph{Vous ferez les constructions suivantes au crayon à papier et en traits fins sauf mention contraire.}
\begin{enumerate}
\item Tracer en noir un cercle $\mathscr{C}$ de centre O et de rayon 4 cm.
\item Placer un point A sur $\mathscr{C}$ en noir.
\item Soit un point B sur $\mathscr{C}$ tel que $\angle{AOB}=10^\circ$ (en tournant dans le sens des aiguilles d'une montre).
\item Construire le point E le milieu de [OB].
\item Construire $\mathscr{C}^\prime$ le cercle de diamètre [BE].
\item Construire ($d$) la droite parallèle à (OA)
passant par B. Elle coupe $\mathscr{C}^\prime$ en G. On notera en rouge le point G.
\item Gommer tout ce qui est au crayon à papier puis recommencer avec d'autres points B en prenant des angles de $10^\circ$ en $10^\circ$ pour construire les points G correspondants.
\end{enumerate}
\end{pasbox}

\begin{enumerate}
\item\par~
\begin{center}
\begin{tikzpicture}
\tkzDefPoint(0,0){O}
\tkzDrawPoint(O)
\tkzLabelPoint(O){O}
\tkzDrawCircle[R](O,4 cm)
\end{tikzpicture}
\end{center}

\newpage

\item\par~
\begin{center}
\begin{tikzpicture}
\tkzDefPoint(0,0){O}
\tkzDrawPoint(O)
\tkzLabelPoint(O){O}
\tkzDrawCircle[R](O,4 cm)
\tkzDefPoint(4,0){A}
\tkzLabelPoint[right](A){A}
\draw[gray!20] (O) -- (A);
\end{tikzpicture}
\end{center}

\item\par~
\begin{center}
\begin{tikzpicture}
\tkzDefPoint(0,0){O}
\tkzDrawPoint(O)
\tkzLabelPoint(O){O}
\tkzDrawCircle[R](O,4 cm)
\tkzDefPoint(4,0){A}
\tkzLabelPoint[right](A){A}
\draw[gray!20] (O) -- (A);
\tkzDefPoint(10:4){B}
\tkzLabelPoint[right](B){B}
\draw[gray!20] (O) -- (B);
\draw[gray!20] (2,0) arc(0:10:2cm);
\node[right,scale=0.75,color=gray!20] at (5:2) {$10^\circ$};
\end{tikzpicture}
\end{center}

\newpage

\item\par~
\begin{center}
\begin{tikzpicture}
\tkzDefPoint(0,0){O}
\tkzDrawPoint(O)
\tkzLabelPoint(O){O}
\tkzDrawCircle[R](O,4 cm)
\tkzDefPoint(4,0){A}
\tkzLabelPoint[right](A){A}
\draw[gray!20] (O) -- (A);
\tkzDefPoint(10:4){B}
\tkzLabelPoint[right](B){B}
\draw[gray!20] (O) -- (B);
\draw[gray!20] (2,0) arc(0:10:2cm);
\node[right,scale=0.75,color=gray!20] at (5:2) {$10^\circ$};
\tkzDefMidPoint(O,B)\tkzGetPoint{E}
\tkzDrawPoint(E)\tkzLabelPoint[above](E){E}
\end{tikzpicture}
\end{center}

\item\par~
\begin{center}
\begin{tikzpicture}
\tkzDefPoint(0,0){O}
\tkzDrawPoint(O)
\tkzLabelPoint(O){O}
\tkzDrawCircle[R](O,4 cm)
\tkzDefPoint(4,0){A}
\tkzLabelPoint[right](A){A}
\draw[gray!20] (O) -- (A);
\tkzDefPoint(10:4){B}
\tkzLabelPoint[right](B){B}
\draw[gray!20] (O) -- (B);
\draw[gray!20] (2,0) arc(0:10:2cm);
\node[right,scale=0.75,color=gray!20] at (5:2) {$10^\circ$};
\tkzDefMidPoint(O,B)\tkzGetPoint{E}
\tkzDrawPoint(E)\tkzLabelPoint[above](E){E}
%\tkzCalcLength[cm](O,B)\tkzGetLength{dEB}
\tkzDrawCircle[diameter,color=gray!20](E,B)
\end{tikzpicture}
\end{center}

\newpage

\item\par~
\begin{center}
\begin{tikzpicture}
\tkzDefPoint(0,0){O}
\tkzDrawPoint(O)
\tkzLabelPoint(O){O}
\tkzDrawCircle[R](O,4 cm)
\tkzDefPoint(4,0){A}
\tkzLabelPoint[right](A){A}
\draw[gray!20] (O) -- (A);
\tkzDefPoint(10:4){B}
\tkzLabelPoint[right](B){B}
\draw[gray!20] (O) -- (B);
\draw[gray!20] (2,0) arc(0:10:2cm);
\node[right,scale=0.75,color=gray!20] at (5:2) {$10^\circ$};
\tkzDefMidPoint(O,B)\tkzGetPoint{E}
\tkzDrawPoint(E)%\tkzLabelPoint[above](E){E}
\tkzDrawCircle[diameter,color=gray!20](E,B)
\tkzDefLine[parallel=through B](O,A)\tkzGetPoint{b}
\tkzDefMidPoint(E,B)\tkzGetPoint{I}
\tkzInterLC[R](B,b)(I,1 cm)\tkzGetPoints{G}{B}
\tkzDrawLine[color=gray!20](B,G)
\tkzDrawPoint[color=red](G)
\end{tikzpicture}
\end{center}

\item\par~
\begin{center}
\begin{tikzpicture}
\tkzDefPoint(0,0){O}
\tkzDrawPoint(O)
\tkzLabelPoint(O){O}
\tkzDrawCircle[R](O,4 cm)
\tkzDefPoint(4,0){A}
\tkzLabelPoint[right](A){A}
\draw[gray!20] (O) -- (A);
\foreach\a in {0,10,...,90}
{
\tkzDefPoint(\a:4){B}
\tkzDefMidPoint(O,B)\tkzGetPoint{E}
\tkzDefLine[parallel=through B](O,A)\tkzGetPoint{b}
\tkzDefMidPoint(E,B)\tkzGetPoint{I}
\tkzInterLC[R](B,b)(I,1 cm)\tkzGetPoints{G}{B}
\tkzDrawPoint[color=red](G)
}
\foreach\a in {100,110,...,180}
{
\tkzDefPoint(\a:4){B}
\tkzDefMidPoint(O,B)\tkzGetPoint{E}
\tkzDefLine[parallel=through B](O,A)\tkzGetPoint{b}
\tkzDefMidPoint(E,B)\tkzGetPoint{I}
\tkzInterLC[R](B,b)(I,1 cm)\tkzGetPoints{B}{G}
\tkzDrawPoint[color=red](G)
}
\foreach\a in {190,200,...,270}
{
\tkzDefPoint(\a:4){B}
\tkzDefMidPoint(O,B)\tkzGetPoint{E}
\tkzDefLine[parallel=through B](O,A)\tkzGetPoint{b}
\tkzDefMidPoint(E,B)\tkzGetPoint{I}
\tkzInterLC[R](B,b)(I,1 cm)\tkzGetPoints{G}{B}
\tkzDrawPoint[color=red](G)
}
\foreach\a in {280,290,...,350}
{
\tkzDefPoint(\a:4){B}
\tkzDefMidPoint(O,B)\tkzGetPoint{E}
\tkzDefLine[parallel=through B](O,A)\tkzGetPoint{b}
\tkzDefMidPoint(E,B)\tkzGetPoint{I}
\tkzInterLC[R](B,b)(I,1 cm)\tkzGetPoints{B}{G}
\tkzDrawPoint[color=red](G)
}
\end{tikzpicture}
\end{center}
\end{enumerate}
\end{document}