A = (1, -2)
B = (5, 3)
C = (9, -2)
F: (5, -2)
e = Segment(B, F)
h = Segment(A, F)
i = Segment(F, C)
p = Segment(B, F)
q = Segment(A, F)
r = Segment(F, C)
γ = Angle(B, F, A)
δ = Angle(A, F, B)
ε = Angle(B, F, C)
hoekbl = 0.8901179185171081 rad (slider from 0 to 90°, step °)
C' = Rotate(C, hoekbl, F)
ζ = Angle(C, F, C')
f = Segment(F, C')
α = Angle(C', F, B)