A = (1, 2)
B = (4, 2)
C = (1, 8)
t1, b, a, c = Polygon(A, C, B)
α = Angle(B, A, C)
f = OrthogonalLine(A, a)
H = Intersect(f, a)
β = Angle(C, H, A)
I = Midpoint(C, B)
g = OrthogonalLine(H, c)
h = OrthogonalLine(H, b)
P = Intersect(h, b)
Q = Intersect(g, c)
i = Line(A, I)
j = Line(P, Q)
G = Intersect(i, j)
γ = Angle(Q, G, I)
k = OrthogonalLine(B, c)
l = OrthogonalLine(C, b)
D = Intersect(i, k)