t = 0.6 (slider from -8 to 8, step 0.1)
A: (cos(t), sin(t))
O = Intersect(xAxis, yAxis)
u = Vector(O, A)
h = 0.1 (slider from 0.01 to 1, step 0.01)
B: (cos(t + h), sin(t + h))
v = Vector(O, B)
w = Vector(A, B)
C: A + w / h
z = Vector(A, C)