unit circle

α

A = Intersect(xAxis, yAxis)
c = Circle(A, 1)
α = 0.5235987755982988 rad (slider from -360° to 720°, step °)
M, D = Intersect(c, xAxis)
B = Rotate(D, α, A)
β = Angle(D, A, B)
a = Ray(A, B)
b = Ray(A, D)
d = OrthogonalLine(B, b)
f = Segment(A, B)
h = OrthogonalLine(B, xAxis)
C = Intersect(h, xAxis)
e = Segment(B, C)
g = Segment(C, A)
k = CircleArc(A, D, B)
text1: "Use slider to set the measure of angle α.
Observe point B " + B + ".
Compare sides BC and AC with point B coordinates.
AB = 1."
i = OrthogonalLine(D, b)
E = Intersect(a, i)
j = Segment(E, D)
γ: 180°
text2: "α = " + α + " = (" + α + "/" + γ + ")π radians ≈ " + k + " radians"