-1.5 5.5 setxrange
-0.5 3 setyrange
50 setxunit
50 setyunit


/A {0 0} def
/B {5 0} def
/E {1.216 0} def
/F {2.838 0} def
/G {2.838 1.622} def
/H {1.216 1.622} def
/P {C A B orthoproj} def

/c {A B diamcercle} def
106.26 c cpoint /C defpoint

A C B angledroit
[A B C] polygone
[E F G H] polygone

/fillstyle {.5 setgray continu hachure} def
[E F G H] polygone* 

[C P] ligne
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1.3 0.8 [1.8 dup] cltexlabel

<latex>
$y$
</latex>
2.75 0.8 [1.8 dup] crtexlabel

<latex>
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2.2 1.51 [1.8 dup] uctexlabel

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1.75 0.8 [1.8 dup] crtexlabel

(A) A [1.5 dup] dltext
(B) B [1.5 dup] drtext
(C) C [1.5 dup] uctext
(E) E [1.5 dup] dctext
(F) F [1.5 dup] dctext
(G) 2.9 1.6 [1.5 dup] uctext
(H) 1.1 1.6  [1.5 dup] uctext

<latex>
$b)$
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-0.4 1.1 [2.0 dup] ultexlabel