-6 7 setxrange
-1 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{-5 3} def
/I{-4 2.75} def
/B{-3 2} def
/J{-2 1.4} def 
/C{0 1} def
/D{2 1.5} def
/E{3 2} def
/F{4 3} def
/G{4.5 4.25} def
/H{5 6} def
1.3 setlinewidth
[A .. I .. B .. J .. C .. D .. E .. F .. G .. H] (*-*) draw
[A B C F H] points

[-5 4 -2 1 ] (<->) ligne
[-1.5 1 1.5 1] (<->) ligne
[3 1 5 5 ] (<->) ligne


#tex# $\rm{T}_1$
-4 4 [1.5 dup] cltexlabel
#tex# $\cal{C}$
2.5 2 [1.5 dup] cltexlabel
#tex# $\rm{T}_2$
1 0.5 [1.5 dup] cltexlabel
#tex# $\rm{T}_3$
4 1 [1.5 dup] cltexlabel