A

B

C

A = (-1, -2)
B = (7, 2)
f: y = 4
C = Point(f)
g = Segment(A, B)
h = Segment(B, C)
i = Segment(C, A)
α = Angle(B, A, C)
β = Angle(A, C, B)
γ = Angle(C, B, A)
k: x(C)
text4: "k=" + (LaTeX[k]) + ""