A = (1.9027967479674792, 2.30436236933798)
B = (6.582977932636469, 4.417022067363529)
C = (8.778857142857145, 0.42457607433217204)
t1, c, a, b = Polygon(A, B, C)
D = Midpoint(A, B)
E = Midpoint(C, B)
α = 3.141592653589793 rad (slider from 0 to 180°, step 0.017453292519943295)
B'_{3} = Rotate(B, α, B)
A' = Rotate(A, (-α), E)
B' = Rotate(B, (-α), E)
C' = Rotate(C, (-α), E)
t1', c', a', b' = Polygon(A', B', C')
A'_{1} = Rotate(A, α, D)
B'_{1} = Rotate(B, α, D)
C'_{1} = Rotate(C, α, D)
t1'_{1}, c'_{1}, a'_{1}, b'_{1} = Polygon(A'_{1}, B'_{1}, C'_{1})
β = Angle(A, B, C)
γ = Angle(C'_{1}, A'_{1}, B'_{1})
δ = Angle(B', C', A')