r

t

S=( \frac{r(1-t^2)}{1+t^2}, \frac{2rt}{1+t^2})

w_0(1-t)^3+w_1 3(1-t)^2t+w_2 3(1-t)t^2+w_3 t^3=1+t^2

A_x(1-t)^3+B_x 3(1-t)^2t+C_x 4 (1-t)t^2+D_x 2 t^3=r(1-t^2)

(w_0,w_1,w_2,w_3)=(1,1,\sfrac{4}{3},2)

A_y(1-t)^3+B_y 3(1-t)^2t+C_y 4 (1-t)t^2+D_y 2
 t^3=2 r t

O = Intersect(xAxis, yAxis)
R = Point(xAxis)
t = 2.1 (slider from -3 to 3, step 0.1)
r = 2
f: y = (t * (x + r))
c = Circle(O, R)
a = CurveCartesian(((r * (1 - tt^(2)))) / (1 + tt^(2)), ((2 * r) * tt / (tt^(2) + 1)), tt, 0, t)
N_2, S = Intersect(c, f)
α = Angle(R, N_2, S)
A: (r, 0)
B: (r, (2 / 3 * r))
C: (r / 2, r)
D: (0, r)
E = (0, 3)
g = Segment(E, O)
F = (3, 0)
h = Segment(N_2, F)
i = Segment(D, C)
j = Segment(C, B)
k = Segment(B, R)
t_g = -0.5 (slider from -8 to 8, step 0.1)
b = CurveCartesian(((r * (1 - tt^(2)))) / (1 + tt^(2)), ((2 * r) * tt / (tt^(2) + 1)), tt, -8, t_g)
N_4: (r, 0)
N_1: (0, r)