%!

% builds the path outlining a square with corners
% (0, 0), (s, 0), (s, s), (0, s)

/buildsquare {
  0 0 moveto
  s 0 lineto
  s s lineto
  0 s lineto
  closepath
} def

% --------------------------------------------------------------

72 dup scale
1 72 div setlinewidth

2.5 5.5 translate

0.6  dup scale

% --- draw the three squares -------------------------------

/s 5 def
gsave
-90 rotate
newpath
buildsquare
stroke
grestore

/s 3 def
gsave
4 3 atan rotate
newpath
buildsquare
stroke
grestore

/s 4 def
gsave
5 0 translate
4 3 atan rotate
newpath
buildsquare
stroke
grestore

% --- the vertical line ------------------------------------------------

% find the vertex (x, y)

/x 3 5 div 3 mul def
/y 4 5 div 3 mul def

% and some analgous ratios
/X 3 5 div 4 mul def
/Y 4 5 div 4 mul def

newpath
x y moveto
0 y 5 add neg rlineto
stroke

% --- the red triangle ------------------------------------------------

newpath
0 0 moveto
x y lineto
0 -5 lineto
closepath
gsave
1 0 0 setrgbcolor
fill
grestore
stroke

% --- the other triangles ------------------------------------------------

newpath
0 0 moveto
y neg x lineto
5 0 lineto
closepath
stroke

newpath
5 0 moveto
5 X add Y lineto
0 0 lineto
closepath
stroke

newpath
5 0 moveto
x y lineto
5 -5 lineto
closepath
stroke

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