α = 0.6632251157578453 rad (slider from 1*° to 179*°, step 1*°)
A = (5, 3)
B = (12, 3)
a = Segment(A, B)
B' = Rotate(B, α, A)
α_2 = Angle(B, A, B')
b = Ray(A, B')
c = OrthogonalLine(A, b)
o = LineBisector(a)
S = Intersect(c, o)
D = Intersect(o, a)
S' = Mirror(S, D)
k = CircleArc(S', B, A)
k' = CircleArc(S, A, B)
E = Point(k)
F = Point(k')
α_3 = Angle(A, E, B)
α_3' = Angle(B, F, A)
e = Segment(A, E)
f = Segment(E, B)
g = Segment(B, F)
h = Segment(F, A)