piste (1, f(1,s))

piste (x_0, f(x_0,s))

s = 0.88875 (slider from 0 to 1, step 0.00000001)
f(x) = If[0 ≤ x ≤ 1, (1 - s) / (1 + x^(2) - ((2 * x) * s))^(2)]
a = Integral(f, 0, 1)
P: (1, f(1))
g: y = y(P)
A = Intersect(f, g, (0.7775, 2.2471910112359557))
b = Integral(f, x(A), 1)