evolvente cerchio, parametrica
x = a (cos(t)+ t * sin(t))
y = a(sin(t)   - t * cos(t))

tangenti (icona4) da punto a cerchio

c = CurveCartesian(3 * (cos(t) + t * sin(t)), 3 * (sin(t) - t * cos(t)), t, 0, 6.28)
C = Point(c)
D = Point(c)
E = Point(c)
F = Point(c)
G = Point(c)
A = Intersect(xAxis, yAxis)
B = Point(xAxis)
d = Circle(A, 3)
a, b = Tangent(D, d)
e, f = Tangent(E, d)
g, h = Tangent(F, d)