Angle de visio

β = 0.4363323129985824 rad (slider from 5° to 65°, step 5°)
M: (1, -8)
L: (1, 1.35974)
A = (0, 0)
C = (2, 6)
D: (2, -6)
E: (4, -6)
F = (4, 6)
poly1, c, d, e, f = Polygon(C, D, E, F)
B = (1.1999742394559132, 0)
G = (1.5, 4)
H = (1.5, -4)
a = Line(G, H)
I = Point(a)
b = OrthogonalLine(I, a)
J = Point(b)
K = (2.456739348827763, 2.172971225610667)
M' = Rotate(M, β, L)
g = Ray(L, M)
h = Ray(L, M')
i = OrthogonalLine(L, g)
p = Circle(L, M')
N = Intersect(p, i, 2)
O = Intersect(p, i, 1)
r = Semicircle(O, N)
k = CircleSector(L, M, M')
q = CircleSector(L, M', N)
α = Angle(M, L, M')