hoekbl = 0.47123889803846897 rad (slider from 0 to 40°, step °)
straal = 3 (slider from 0 to 5, step 0.1)
A = (-8, -15)
c = Circle(A, straal)
B = Point(c)
f = Line(A, B)
H = Intersect(c, f, 2)
j = Segment(B, H)
F = Point(j)
h = OrthogonalLine(B, j)
G = Point(h)
D = Rotate(F, (-hoekbl), B)
g = Segment(D, B)
α = Angle(G, B, D)
β = Angle(H, B, D)
i = Segment(G, B)