autocrop
17 setxunit
10 setfontsize
/r 5 def
/cerc {O r} def
/A {85 cerc cpoint} def
/B {-152 cerc cpoint} def
/C {-20 cerc cpoint} def
/H {A B C orthoproj} def
A O cerc interdroitecercle popp /D defpoint
A D B C interdroite /E defpoint

.8 setlinewidth

cerc cercle
[A B C] polygone
[H A] ligne
[B D A] ligne

A H C angledroit
A B D angledroit

[E A B C D H O] points

B E D .7 (=) tripointarc
C E A .7 (=) tripointarc
A C B .7 (-) tripointarc
A D B .7 (-) tripointarc

1.2 setlinewidth
[B C A D] polygone

setTimesItalic
   (O) O bltext
   (A) A urtext
   (B) B dltext
   (C) C drtext
   (D) D drtext
   (H) H drtext
   (E) E drtext
   (c) A B milieu ultext
   (b) A C milieu urtext
   (h) A H milieu brtext
   (r) A O milieu bltext