A = (5.58, 5.36)
B = (3.609237977916274, 2.7449345990034058)
C = (7.949058577586952, 4.801690067252243)
poly1, c, a, b = Polygon(A, B, C)
d = Line(A, a)
e = Segment(B, C)
D = Point(d)
E = Point(d)
f = Segment(D, E)
α = Angle(C, B, A)
β = Angle(A, C, B)
θ = Angle(B, A, C)
s: α + β + θ
text1: "Angle \; sum = \alpha + \beta+\theta= " + (LaTeX[s]) + ""