$(10y+30)°$

$(5x+3y)°$

$(3x+20)°$

A = (1, 2)
B = (9, 2)
C = (3, 6)
poly1, c, a, b = Polygon(A, B, C)
α = Angle(B, A, C)
β = Angle(A, C, B)
γ = Angle(C, B, A)