A = 1 (slider from 0 to 9, step 0.1)
O = (0, 0)
B: (sqrt(A), 0)
C: (sqrt(A), sqrt(A))
D: (0, sqrt(A))
Vieleck1, a_1, b, c, d = Polygon(O, B, C, D)
P: (Vieleck1, sqrt(A))