%@AUTEUR:Guillaume Connan

prologues:=2;

verbatimtex
%&latex
\documentclass{article}
\usepackage[upright]{fourier}
\begin{document}
etex

input geometriesyr16

figure(0,0,6cm,6cm);
pair M,N,P,O;
path cc;

O:=(3cm,3cm);

drawarrow (3cm,0)--(3cm,6cm);drawarrow (0,3cm)--(6cm,3cm);

cc:=cercles(O,2cm);
trace grille(0.5) withcolor .5white;

trace cc withpen pencircle scaled 1.1bp withcolor 0.5white;

M:=pointarc(cc,135);
N:=pointarc(cc,210);
P:=pointarc(cc,120);

dotlabel.ulft(btex M etex,M );
dotlabel.top(btex P etex,P );
dotlabel.llft(btex N etex,N );
label.lrt(btex O etex,O );
label.bot(btex \footnotesize $\cos\left(\frac{2\pi}3\right)=-\frac12$ etex,(2cm,3cm) );
label.rt(btex \footnotesize $\sin\left(-\frac{5\pi}{6}\right)=-\frac12$ etex,(3cm,2cm) );

draw O--M dashed evenly;
draw P--(2cm,3cm) dashed evenly;
draw N--(3cm,2cm) dashed evenly;
fin;

end