%auteur : Peric
56.90 setxunit
-1.6 2.5 setxrange
-1.3 1.5 setyrange
1 1 settkstep
1 1 setmkstep
%ticks
/t {2} def
/h {0.1} def


/xmarkstyle {[1.5 dup] dltext} def
/ymarkstyle {[1.5 dup] ultext} def
[-1] {xmark} apply
[1 ] {ymark} apply
/xmarkstyle {[1.5 dup] drtext} def
/ymarkstyle {[1.5 dup] dltext} def
[1] {xmark} apply
[-1] {ymark} apply
traceaxes
%axesarrow
unites


/B {60 dup cos exch sin} def
/C {-60 dup cos exch sin} def
/D {90 dup cos exch sin} def
/O {0 0} def
 
1 setlinewidth

<latex>
$\frac{\pi}{3}$
</latex>
 B  [t dup ] urtexlabel
<latex>
$\frac{\pi}{2}$
</latex>
 D  [t dup ] urtexlabel
(O) O [t dup] dltext
<latex>
$\frac{1}{2}$
</latex>
 0.5 0  [t dup ] ultexlabel
<latex>
$\textrm{cos }\alpha\geqslant\frac12$
</latex>
 1 -1.3  [1.5 dup ] urtexlabel
[1 -1 0.75 -0.4] ligne
gsave
1 setlinewidth
O 1 cercle

grestore

gsave
newpath
B smoveto
%B lineto
-60 60 0 0 1 Cercle_
clip
hachure
3 setlinewidth noir 
stroke 
grestore

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