input geometriesyr16;

figure(0,0,7.5u,4.5u);
pair O,A,B,C,D,E;
trace grille(0.5) withcolor orange;
O=pp(2,7);
A-O=pp(-2,-4);
B-O=pp(3,-6);
C-O=pp(6,-3);
D-C=O-A;
E-C=pp(6,0);
drawarrow O--A;
trace appelation(A,O,2mm,
  btex $\overrightarrow{\strut a}$ etex);
drawarrow O--B;
trace appelation(O,1/2[A,C],2mm,%
  btex $\overrightarrow{\strut e}$ etex);
drawarrow O--C;
trace appelation(O,C,2mm,%
  btex $\overrightarrow{\strut c}$ etex);
drawarrow A--C;
trace appelation(A,C,2mm,
btex $\overrightarrow{\strut d}$ etex);
drawarrow C--B;
trace appelation(B,C,2mm,
  btex $\overrightarrow{\strut b}$ etex);
drawarrow D--C;
trace appelation(C,D,2mm,
  btex $\overrightarrow{\strut a}$ etex);
drawarrow C--E;
trace appelation(C,E,2mm,
  btex $\overrightarrow{\strut g}$ etex);
drawarrow E--D;
trace appelation(D,E,2mm,
  btex $\overrightarrow{\strut h}$ etex);
drawarrow E--B;
trace appelation(B,E,-4mm,
  btex $\overrightarrow{\strut f}$ etex);
drawarrow O--D;
trace appelation(O,D,2mm,
  btex $\overrightarrow{\strut k}$ etex);
fin;

end