p: 4 / 3
eps: sqrt(5) / 3
r(x) = p / (1 - (eps * cos(x)))
θ = 6.283185307179594 (slider from (-2 * π) to 7, step π / 60)
P = CurveCartesian((r(θ) * cos(θ)), (r(θ) * sin(θ)), θ, 0, (2 * π))
A: (r(θ); θ)
r'(x) = r'(x)
m: ((r'(θ) * sin(θ)) + (r(θ) * cos(θ))) / ((r'(θ) * cos(θ)) - (r(θ) * sin(θ)))
f: y = (m * (x - x(A))) + y(A)
B = (-7.790909090909095, 2.472727272727273)
C = (-6.663636363636362, 2.472727272727273)