-1.5 1 setxrange
-0.3 1 setyrange

/A {-0.7 0} def
/B {0.7 0} def
/M {A B milieu} def

/c {A B diamcercle} def
/c1 {A M diamcercle} def
70 c1 cpoint /C defpoint
70 c cpoint /P defpoint

A P B angledroit
[A B C] polygone
 
gsave
pointilles
[C P] ligne
[P B] ligne
grestore
[A B C P] points
0 180 c Cercle 

(A) A [1.5 dup] dltext
(B) B [1.5 dup] drtext
(C) C [1.5 dup] uctext
(P) P [1.5 dup] uctext

<latex>
$\rm{Abb}.\,4$
</latex>
-1 0.3 [2.0 dup] ultexlabel