-11 10 setxrange
-1 11 setyrange

10 setfontsize
17 setxunit
/f {.5 mul 5 add} def

/A {4 dup f} def
/B {8 dup f} def
/C {-5 dup f} def
/D {-3 dup f} def
/C' {C pop 1} def
/D' {D pop 1} def
/C" {C exch pop -7 exch} def
/D" {D exch pop -7 exch} def

traceaxes
axesarrow
%quadrillage

/point {times2} def
[A B] dashpoints
[0 dup f C D] points

1.2 setlinewidth
{f} courbe

setTimesItalic
   (O) O dltext
   (A) A uctext
   (B) B uctext
   (x) xmax 0 dltext
   (y) 0 ymax dltext

gsave
   .7 setlinewidth
   0 6 stranslate
   [A projx B projx] (<->) ligne
grestore

gsave
   .7 setlinewidth
   3 0 stranslate
   [A projy B projy] (<->) ligne
grestore

gsave
   .7 setlinewidth
   pointilles
   [C C'] ligne
   [D D'] ligne
   continu
   0 .5 stranslate
   [C' D'] (<->) ligne
   setTimes
   (1) C' D' milieu uctext
grestore

gsave
   .7 setlinewidth
   pointilles
   [C C"] ligne
   [D D"] ligne
   continu
   .5 0 stranslate
   [C" D"] (<->) ligne
grestore

<tex>
$y = ax + b$
</tex>

-9 dup f {A B angle} uctexlabel