p = 3.1 (slider from 2.5 to 20, step 0.1)
c: y^(2) = ((4 * p) * x)
F: (p, 0)
A: (p - 5, 0)
a: y = x - (p - 5)
B = Intersect(c, a, 1)
C = Intersect(c, a, 2)