-1.5 3.5 setxrange
-1 3.3 setyrange
50 setxunit
50 setyunit
/A {-0.5 0} def
/B {2.7 0} def
/D {1.8 3} def
/M {B D mediatrice} def
M A D interdroite /C defpoint
B C 2 marked
D C 2 marked
[B C] ligne
[A B D] polygone
D B C 0.4 (-) tripointarcarrow
C D B 0.4 (-) tripointarcarrow
D B C 0.45 (-) tripointarcarrow
C D B 0.45 (-) tripointarcarrow
gsave
pointilles
D B A 0.6 (-) tripointarcarrow
grestore
$a$
1.6 0.43 [1.8 dup] ultexlabel
$b$
-0.52 0.52 [1.8 dup] crtexlabel
$c$
1.1 0.05 [1.8 dup] dctexlabel
$a$
0.8 2.2 [1.8 dup] dctexlabel
(A) A [1.5 dup] dltext
(B) B [1.5 dup] drtext
(C) C [1.5 dup] ultext
(D) D [1.5 dup] uctext
$\mathrm{Abb.}\, 2$
1.6 -1 [2.0 dup] ultexlabel