n = 3 (slider from 0 to 20, step 1)
A = (-1, -1)
B = (1, -1)
poly1, a, b, c, d, C, D = Polygon(A, B, 4)
liste1 = Sequence((sqrt(2) / (k + 1); -3 * π / 4 + k * π / 2), k, 0, n)
liste2 = Sequence(Segment[Element[liste1, k + 1], Element[liste1, k + 2]], k, 0, n - 1)
Long = Sum(liste2)
texte1: "Longueur de la spirale = " + Long
e = Segment(D, B)
f = Segment(C, A)
O = (0, 0)
I = (1, 0)
J = (0, 1)