input geometriesyr16; figure(-10cm,-10cm,10cm,10cm); pair O,I,J; marque_p:="croix"; u:=0.5cm; O=(0,0); J=(0,2u); I=(2u-u/4,0); drawarrow (-8u,0)--(8u,0)withpen pencircle scaled 1bp; drawarrow (0,-8u)--(0,8u)withpen pencircle scaled 1bp; for i=-8u step 2u until 8u: draw (i,u/10)--(i,-u/10)withpen pencircle scaled 1bp; endfor; for i=-8u step 2u until 8u: draw (u/10,i)--(-u/10,i)withpen pencircle scaled 1bp; endfor; for i=-8u step u until 8u: draw (i,-8u)--(i,8u); endfor; for i=-8u step u until 8u: draw (-8u,i)--(8u,i); endfor; label.llft("O",O); label.bot("1",I); label.lft("1",J); fin; end