Stein = (0, 5)
r = 0 (slider from 0 to 8, step 0.5)
Wellen = Circle(Stein, r)
B = Point(Wellen)
a = Segment(Stein, B)
f(x) = 0.0
A = Point(f)
C = Point(f)
D = (36.117321803862566, -19.053907942610522)
E = (-28.87329547189612, -19.563067786964535)
Vieleck1, a_1, c, d, e = Polygon(A, C, D, E)