Sum of the Angles in a Triangle

A = (2.5, -0.54)
B = (3.72, 2.16)
C = (6.34, -0.52)
poly1, c, a, b = Polygon(A, B, C)
α = Angle(C, A, B)
β = Angle(A, B, C)
γ = Angle(B, C, A)