t = 9.4 (slider from -10 to 10, step 0.01)
b: x = t
M = Intersect(b, a)
c = Circle(M, 1.0)
B = Point(xAxis)
C = Point(xAxis)
d = Line(B, C)
D = Intersect(b, d)
P = Rotate(D, -(t), M)
α = Angle(D, M, P)
e = Segment(M, P)
f = Segment(P, M)