m∠POA

P'

S'

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)
g = Line(O, P)
S: (α, sin(α))
C: (cos(α), 0)
i = Segment(P, C)
l = OrthogonalLine(S, xAxis)
D = Intersect(l, xAxis)
m = Segment(S, D)
p: x = 4
q = OrthogonalLine(P, p)
E = Intersect(p, q)
u = Vector(P, E)
G = Point(xAxis)
s = OrthogonalLine(G, xAxis)
t = OrthogonalLine(S, s)
I = Intersect(s, t)
v = Vector(I, S)
h = OrthogonalLine(C, xAxis)
B: (x(P), y(P) + 2.8)
j = Segment(P, B)
k = OrthogonalLine(B, p)
F = Intersect(p, k)
w = Vector(B, F)
R: (α, sin(α) + 2.8)
n = OrthogonalLine(R, s)
H = Intersect(s, n)
a = Vector(H, R)