r_1 = 1.6 (slider from 0 to 5, step 0.1)
C_1 = (1, 0)
P = (-0.30090324567522214, 0.4835285764369367)
C_f = (0, 0)
a = Line(C_f, P)
c = Circle(C_1, r_1)
PP_1, P_1 = Intersect(c, a)
b = OrthogonalLine(C_1, a)
H = Intersect(b, a)
d = Segment(H, C_1)
X_P: (x(P), 0)
e = Segment(P, X_P)
α = Angle(C_1, H, C_f)