m∠POA

c: x^(2) + y^(2) = 1
P = Point(c)
O = Intersect(xAxis, yAxis)
A = Point(c)
f = Segment(P, O)
α = Angle(A, O, P)
Q: (α, sin(α))
g = OrthogonalLine(P, xAxis)
B = Intersect(g, xAxis)
h = Segment(P, B)
i = OrthogonalLine(Q, xAxis)
C = Intersect(i, xAxis)
j = Segment(Q, C)
D = Point(xAxis)
k = OrthogonalLine(D, xAxis)
S: (-11, sin(α))
u = Vector(S, Q)
l: x = 4
R: (4, sin(α))
v = Vector(P, R)