Iga kolmnurga nurkade summa on 180°

A = (2.1042117080858453, -1.6094049155054706)
B = (7.18573560178103, 4.103263665623174)
C = (10.68130617833568, -0.492764314661628)
t1, c, a, b = Polygon(A, B, C)
D = Midpoint(A, B)
E = Midpoint(B, C)
f = Segment(D, A)
g = Segment(D, B)
h = Segment(B, E)
i = Segment(E, C)
j = Segment(C, A)
α = Angle(C, A, D)
β = Angle(D, B, E)
γ = Angle(E, C, A)
F = Midpoint(A, C)
t2, f_1, a_1, d = Polygon(A, D, F)
t3, c_1, e, f_2 = Polygon(E, F, C)
δ = 0 rad (slider from 0 to 180°)
ε = 0 rad (slider from 0 to 180°)
A' = Rotate(A, (-δ), D)
D' = Rotate(D, (-δ), D)
F' = Rotate(F, (-δ), D)
t2', f', a', d' = Polygon(A', D', F')
E' = Rotate(E, ε, E)
F'_1 = Rotate(F, ε, E)
C' = Rotate(C, ε, E)
t3', c', e', f'_1 = Polygon(E', F'_1, C')
ζ = Angle(F', A', D')
η = Angle(E', C', F'_1)