A = (-3, 1)
B = (1, 1)
C = (-1, 5)
a = Segment(A, B)
b = Segment(B, C)
c = Segment(A, C)
H = (-1, 1)
d = Segment(C, H)
α = Angle(B, H, C)
β = Angle(C, H, A)
γ = Angle(A, C, H)
δ = Angle(H, C, B)