r = 1.7 (slider from 0.2 to 5, step 0.1)
O = (-2.828712847414411, 4.178727207330659)
c = Circle(O, r)
B = Point(c)
E = Point(c)
C = Point(c)
D = Point(c)
a = Segment(D, C)
b = Segment(B, E)
A = Intersect(a, b)
d = Segment(B, A)
e = Segment(C, A)
f = Segment(D, A)
g = Segment(A, E)
h = Segment(B, D)
α = Angle(B, A, C)
β = Angle(A, B, D)
γ = Angle(B, D, A)
k = CircleArc(O, B, C)
p = CircleArc(O, E, D)