% --- start of displayed preamble in the book ---
input geometriesyr16
% --- end of displayed preamble in the book ---
defaultfont:="ptmr8r";
warningcheck:=0;
beginfig(1)
figuremainlevee(0,0,5u,5u);
  trace grille(1) withcolor gris;
  origine((3,2));
  trace axes;
  pair A,B,C;
  A=placepoint(-2,-1);
  B=placepoint(1,-1); C=placepoint(1,2);
  trace polygone(A,B,C) withcolor rouge;
  trace cercles(A,B,C) withcolor bleu;
  nomme.llft(A);  nomme.lrt(B);
  nomme.top(C);
finmainlevee;
endfig;
end;