180°

180°

\alpha+\beta+\gamma=180^\circ

A_1 = (-3, -6.04)
B_1 = (29, -6.04)
f = Segment(A_1, B_1)
C_1 = (8, 0.96)
D = Point(f)
E = Point(f)
F = (4, 0)
G = (4, -5.76)
H = (14.7, -5.76)
I = (15, 0)
q1, f_1, g, h_1, i = Polygon(F, G, H, I)
B = PointIn(q1)
A_2 = Point(f)
C_2 = Point(f)
C = Point(f)
J = Point(f)
h = Segment(C_2, J)
A = Point(h)
t1, c, a, b = Polygon(A, B, C)
j = Ray(A, B)
k = Ray(C, B)
l = Line(B, b)
K = Point(l)
L = Point(k)
M = Point(j)
N = Point(l)
α = Angle(C, A, B)
β = Angle(A, B, C)
γ = Angle(B, C, A)
γ' = Angle(L, B, K)
β' = Angle(M, B, L)
α' = Angle(N, B, M)
η = Angle(N, B, K)
O = Point(l)
P = (6.58, -0.08)
S = (8.64, -0.04)
m = Line(B, f)
Q = Point(m)
R = Point(m)
δ = Angle(Q, B, R)