A = (0, 0)
B' = (4, 0)
f = Line(A, B')
c = Semicircle(A, B')
C' = Point(c)
t1, h, a, b = Polygon(A, B', C')
B = Point(f)
g = Line(B, a)
i = Line(A, C')
β = Angle(B', A, C')
C = Intersect(g, i)
t2, d_1, a_1, c_1 = Polygon(A, B, C)