A = (-6, 5)
B = (-4, 5)
c = Circle(A, B)
C = Point(c)
f = Segment(A, C)
D = Point(c)
g = Segment(D, A)
d = CircleSector(A, C, D)
u = Vector((0, 0), (5, 0))
d' = Translate(d, u)
C' = Translate(C, u)
A' = Translate(A, u)
D' = Translate(D, u)
α = Angle(C, A, D)
a: ((1 / 2 * f) * sec((1 / 2 * α)))
h(x) = If[0 < x < 1.5708, ((1 / 2 * f) * sec((1 / 2 * x))), If[1.5708 ≤ x ≤ 3.141592653589793, (f * cos((1 / 2 * x) - π / 2)), If[3.141592653589793 < x < 6.28319, Length[f], If[x ≟ 0, 0]]]]
h' = Derivative(h)
h'' = Derivative(h, 2)
E = Center(Circle[A', D', C'])
b: h(α)
t1, c', a', i = Polygon(A', D', C')
F = Midpoint(c')
G = Midpoint(a')
H = Midpoint(i)
j = Segment(F, C')
k = Segment(G, A')
l = Segment(D', H)
I = Intersect(l, k)
e = Circle(I, b)