-8.5 10.5 setxrange
-5.5 7.5 setyrange
25 setxunit
%50 setyunit

/quadrillagewidth[.7 .4 .1] def
[1 1 ]{.7 setgray} Quadrillage

1.2 setlinewidth
%0.5 0.5 setsubtkstep
traceaxes
ticks
%marks
%tracerepere
axesarrow
(-5) -5 0 [1.5 dup] dctext
(0) 0 0 [1.5 dup] dltext
(1) 1 0 [1.5 dup] dctext
(5) 5 0 [1.5 dup] dctext
(1) 0 1 [1.5 dup] cltext
(5) 0 5 [1.5 dup] cltext

/A{-7 -4} def
/B{-6 0} def
/C{-4 2} def
/D{-1 1} def
/E{0 2} def
/F{1 4} def
/G{4 6} def
/H{6 4} def
/I{6.5 2} def
/J{7 0} def
/K{8 -3} def
1.3 setlinewidth
[A .. B .. C .. D{right} .. E .. F .. G{right} .. H .. I .. J .. K] (*-*) draw
[A F K C H] points

[-3 -2 3 7 ] (<->) ligne
[-6 2 -2 2] (<->) ligne
[7 1 5 7 ] (<->) ligne
[-7 -2 -5 2 ] (<->) ligne

#tex# $\rm{T}_1$
-5 2.5 [1.5 dup] cltexlabel
#tex# $\rm{T}_2$
-1.5 -2 [1.5 dup] cltexlabel
#tex# $\rm{T}_3$
6 7 [1.5 dup] cltexlabel