-1 1 setxrange
-1 1 setyrange
/X {-0.7 0} def
/Y {0.7 0} def
/M {X Y milieu} def
/c {X Y diamcercle} def
75 c cpoint /C defpoint
225 c cpoint /A defpoint
315 c cpoint /B defpoint
[A B C] polygone
[M A] ligne
B A C 0.12 (-) tripointarc
C B A 0.12 (-) tripointarc
A C B 0.12 (-) tripointarc
[A B C M] points
0 3600 c Cercle
(A) A [1.5 dup] dltext
(B) B [1.5 dup] drtext
(C) C [1.5 dup] uctext
(M) M [1.5 dup] uctext
$a$
0.5 0 [1.6 dup] ultexlabel
$c$
0.1 -0.62 [1.6 dup] ultexlabel
$b$
-0.15 0 [1.6 dup] ultexlabel
$r$
-0.1 -0.2 [1.6 dup] ultexlabel
$\gamma$
0.25 0.4 [1.6 dup] ultexlabel
$\alpha$
-0.4 -0.48 [1.6 dup] urtexlabel
$\beta$
0.28 -0.49 [1.6 dup] urtexlabel