f(x)=

xs = 1 (slider from -5 to 5, step 0.5)
ys = 1 (slider from -5 to 5, step 0.5)
a = 1 (slider from -4 to 4, step 0.2)
f(x) = (a * (x - xs)^(2)) + ys
S = Extremum(f)
B = Point(Circle[S, 1])
g = Segment(S, B)
C = Point(Circle[S, -1])
B' = Mirror(B, S)
h = OrthogonalLine(B, xAxis)
i = OrthogonalLine(B', xAxis)
E = Intersect(f, i)
F = Intersect(f, h)
j = Segment(B', S)
k = Segment(S, B)
l = Segment(B, F)
m = Segment(B', E)
Text1 = LaTeX($1)