a = 3 (slider from 1.5 to 6, step 0.1)
B = Intersect(a, b)
C = Intersect(c, b)
D = Point(Circle[C, (2 * a) - 3])
d = Segment(C, D)
e = OrthogonalLine(D, b)
f = Circle(D, a + 1)
E = Intersect(f, e, 2)
g = Line(E, b)
F = Intersect(c, g)
poly1, f_1, e_1, d_1, c_1 = Polygon(F, E, D, C)