vertex form of parabola
Author: Farrar

y=(x-h)²+k

h = -2 (slider from -10 to 10, step 1)
k = 2 (slider from -10 to 10, step 1)
f(x) = (x - h)^(2.0) + k
A = Intersect(xAxis, yAxis)
B: (x(A), y(A) + k)
C: (x(A) + h, y(A))
a = Segment(A, C)
b = Segment(A, B)