-0.5 4.5 setxrange
-1 3 setyrange
50 setxunit
50 setyunit

/A {0 0} def
/B {4 0} def
/C {1.5 2.5} def
/D {2 1} def
/E {A D B C interdroite} def


[A B C] polygone
[A D B] polygone

gsave
pointilles
[D E] ligne
grestore

(A) A [1.5 dup] dltext
(B) B [1.5 dup] drtext
(C) C [1.5 dup] uctext
(E) E [1.5 dup] urtext
(D) D [1.5 dup] ultext

<latex>
$\rm{Abb}.\,3$
</latex>
2.3 -1 [2.0 dup] ultexlabel