A = Point(xAxis)
B = Point(xAxis)
a = Segment(A, B)
U = 20 (slider from 0 to 30, step 0.5)
f = Function((20 - 2 x) / 2 x, 0, U / 2)
c = Circle(B, (U - 2 a) / 2)
b = OrthogonalLine(B, xAxis)
C_1, C = Intersect(c, b)
d = Line(A, b)
e = Line(C, a)
D = Intersect(d, e)
V, a_1, b_1, c_1, d_1 = Polygon(A, B, C, D)
P: (a, f(a))