Kolmnurga  \; sisenurkade \; summa \; on  \; 180⁰. 

A = (4.6, -2.45)
B = (11.4, 3.93)
C = (-4.126666666666671, 1.14)
t1, c, a, b = Polygon(A, B, C)
α = Angle(B, A, C)
β = Angle(C, B, A)
γ = Angle(A, C, B)
δ = 0 rad (slider from 0 to 180°, step 10°)
ε = 0 rad (slider from 0 to 180°, step 10°)
D = Midpoint(A, C)
E = Midpoint(A, B)
A' = Rotate(A, (-δ), D)
B' = Rotate(B, (-δ), D)
C' = Rotate(C, (-δ), D)
t1', c', a', b' = Polygon(A', B', C')
A'_{1} = Rotate(A, ε, E)
B'_{1} = Rotate(B, ε, E)
C'_{1} = Rotate(C, ε, E)
t1'_{1}, c'_{1}, a'_{1}, b'_{1} = Polygon(A'_{1}, B'_{1}, C'_{1})
ζ = Angle(C, A, B')
η = Angle(C'_{1}, A, B)