a = -4.07 (slider from -10 to 10, step 0.01)
A = (1, 0)
O = (0, 0)
c = Circle(O, 1.0)
M = Rotate(A, a, O)
α = Angle(A, O, M)
A'_2 = Rotate(A, 3.141592653589793 / 2.0 - a, O)
A' = Rotate(A, 3.141592653589793 / 2.0 + a, O)
γ = Angle(A, O, A')
S: (a, y(M))
C: (a, x(M))
T: (a, y(M) / x(M))