a = 1.6 (slider from 0 to 2, step 0.2)
b = 0.8 (slider from 0 to 1, step 0.1)
bib = CurveCartesian(t^(2) - b^(2), ((2 * t) * b), t, 0, 2)
b_s = CurveCartesian(t, b, t, 0, 2)
bia = CurveCartesian(a^(2) - t^(2), ((2 * a) * t), t, 0, 1)
a_s = CurveCartesian(a, t, t, 0, 1)
l1 = Sequence(CurveCartesian[a, t, t, 0, 1], a, 0, 2, 0.2)
l2 = Sequence(CurveCartesian[t, b, t, 0, 2], b, 0, 1, 0.1)
l3 = Sequence(CurveCartesian[a^(2) - t^(2), ((2 * a) * t), t, 0, 1], a, 0, 2, 0.2)
l4 = Sequence(CurveCartesian[t^(2) - b^(2), ((2 * t) * b), t, 0, 2], b, 0, 1, 0.1)
B = Point(b_s)
A = Point(a_s)
A': (x(A)^(2) - y(A)^(2), ((2 * x(A)) * y(A)))
B': (x(B)^(2) - y(B)^(2), ((2 * x(B)) * y(B)))