a = 1.4 (slider from -5 to 5, step 0.1)
c: 1.0 * 1.0 * 1.0 y = 1.0 * 1.0 * 1.0 x^(2.0) - 2.0 * a * 1.0 * 1.0 * 1.0 x + 1.0
A = Vertex(c)