Ricerca della tangente in A

f(x) = x^(3)
x_B = 1.18 (slider from 1 to 1.5, step 0.01)
A: (1, f(1))
B: (x_B, f(x_B))
s = Line(A, B)
Δx: x(B) - x(A)
Δy: f(x(B)) - f(x(A))
m = If(Δx ≠ 0, Δy / Δx)
t = Tangent(A, f)