S1 = 1 (slider from 0 to 8, step 0.1)
S2 = 2 (slider from 0 to 5, step 0.1)
A: (S1, S2)
B: (4, S2)
C = (4, 4)
D: (S1, 4)
Fläche, a, b, c, d = Polygon(A, B, C, D)