Hilfslinien

A = (-20, 1)
B = (-15, 1)
f = Segment(A, B)
C = (-19.29772757623506, 3.2498999209052752)
g = Line(C, f)
c = Circle(A, C)
r = Segment(A, C)
d = Circle(B, r)
D, E = Intersect(d, g)
h = Segment(C, D)
i = Segment(D, B)
F = Midpoint(A, C)
G = Midpoint(D, B)
j = OrthogonalLine(F, r)
k = OrthogonalLine(G, i)
M = Intersect(j, k)
e = Circle(M, C)
α = Angle(A, F, M)
β = Angle(D, G, M)
a = true