isoskeles_korifis_gonias

a = Segment(A, B)
B' = Rotate(B, 180.0° - 2.0 * α, A)
β = Angle(B, A, B')
A' = Rotate(A, -(180.0° - 2.0 * α), B)
γ = Angle(A', B, A)
b = Line(A, B')
c = Line(B, A')
C = Intersect(c, b)
d = Segment(A, C)
e = Segment(B, C)