P (cos(α) / sin(α))

1

sin(α)

cos(α)

1

α

0

1

1

-1

-1

A = Intersect(xAxis, yAxis)
c = Circle(A, 1.0)
B = Point(c)
C = Point(xAxis)
Vieleck1, c_1, a, b = Polygon(A, B, C)
u = Vector(A, B)
A' = Rotate(A, 270.0*°, C)
α = Angle(A', C, A)
β = Angle(C, A, B)
D = (0, 0)
E = (0, 1)
F = (1, 0)
G = (0, -1)
H = (-1, 0)