A = Point(yAxis)
B = Point(xAxis)
C = Point(yAxis)
D = Point(xAxis)
poly1, a, b, c, d = Polygon(A, B, C, D)
E = Intersect(xAxis, yAxis)
e = Circle(E, D)
α = 0 rad (slider from 0 to 6.283185307179586, step 0.1°)
D' = Rotate(D, α, E)
β = Angle(D, E, D')
f = Segment(E, D')
F = Intersect(f, poly1)
g = Circle(F, D')