a = 0 rad (slider from 0 to 6.283185307179586, step 0.017453292519943295)
A = Point(c)
B = Point(xAxis)
A' = Rotate(A, a, B)
α = Angle(A, B, A')
C: (a, 0)
D: (a, sin(a))
E: (cos(a), 0)
b = Segment(D, C)
d = Segment(E, A')
e = Segment(B, E)
f = Segment(B, A')
F: (a, cos(a))
g = Segment(F, C)