t = 2 (slider from 0 to 9, step 1)
A = Point(xAxis)
f = Line(A, yAxis)
C: (x(A), t)
D: C + (0, 1)
B: (0, 0.5)
g = Ray(B, C)
h = Ray(B, D)
t1, b, c, d = Polygon(C, D, B)
β = Angle(C, B, D)