-1.2 1.2 setxrange
-1.2 1.2 setyrange
jpegmode
/cerc {O 1} def
/alpha 40 def

10 setfontsize
/m {alpha cerc cpoint} def
/A {m projx} def
/B {m projy} def
/M {m A B orthoproj} def

traceaxes
axesarrow
ticks
marks
cerc cercle

m dashpoint
[A m B M] points

gsave
   mixte
   A B 1.2 trait
   M m 1.1 trait
grestore
/@ngledr@it 4 def
 
A M m angledroit


/X {settvar
    t Cos 3 exp
} def
/Y {settvar
    t Sin 3 exp
} def

/X' {settvar
    t Cos 2 exp -3 mul t Sin mul
} def
/Y' {settvar
    t Sin 2 exp 3 mul t Cos mul
} def

/dessin {
   tracerepere
   marks
   1 dict begin
   1.5 setlinewidth
   gsave
	 bleu
	 {X} {Y} courbeparam
   grestore
   end
} def

 
dessin
 
setTimesItalic
   (A) A 0 .1 subv dtext
   (B) B 0 .05 subv dltext
   (O) O drtext
   (m) m utext
   (M) M dltext


.8 settailletangente
pi 3 mul 4 div (X) (Y) ptangente
pi -3 mul 4 div (X) (Y) ptangente
pi -4 div (X) (Y) ptangente