r = 1

arc(α)

P'

sin(α)

arc(α)

Der Sinus 
am Einheitskreis

M = Point(xAxis)
c = Circle(M, 1)
P = Point(c)
a = Segment(M, P)
b = OrthogonalLine(P, xAxis)
A = Intersect(b, xAxis)
d = Segment(P, A)
α = Angle(xAxis, a)
r: α / °
B = Intersect(c, xAxis, 2)
e = CircleArc(M, B, P)
S = If(e > π, (e, (-d)), (e, d))
f = OrthogonalLine(S, xAxis)
C = Intersect(f, xAxis)
g = Segment(S, C)
D = Intersect(xAxis, yAxis)
h = Segment(D, C)
i = Segment(P, S)
Text1: "α = " + α + "
arc(α) = " + e + "
sin(α) = " + d + ""
Sa: (x(S), y(S))
E = Point(xAxis)
F = Point(h)
j = Segment(F, E)