Graphing cos(x): Cosine and the Unit Circle
Author: LFS

Unit Circle

y=cos(x)

Click and drag the point on the slider below.

The arc-length of the sector is the length along the horizontal axis! 
This is a number - not degrees! 

Notice that the graph is drawn to scale 1:1.

α = 3.141592653589793 rad (slider from 0 to 6.283185307179586, step 0.017453292519943295)
f(x) = cos(x)
O = Point(yAxis)
B: (-1.0 * 2.0, y(O))
a = Line(B, O)
c = Circle(O, 1.0)
C = Intersect(c, a, 2.0)
D = Rotate(C, α, O)
e = OrthogonalLine(D, a)
A = Intersect(a, e)
β = Angle(C, O, D)
b = Segment(O, D)
d = Distance(D, a)
RadianAlpha: α * 3.141592653589793 / 180.0 / °
T1: "α\, =\, " + α + "\, =\, " + α + "\,\cdot1\,=\, " + α + "\cdot\frac{π}{180°}\, =\, " + RadianAlpha + "\,(radians)"
A_1: (RadianAlpha, 0.0)
D_1: (RadianAlpha, x(A))
h = Segment(A_1, D_1)
sinus: x(A)
T3: sinus + ""
E = Midpoint(O, A)
F = Midpoint(A_1, D_1)
T2: sinus + ""
G = Point(xAxis)
i = Segment(G, A_1)
H = Intersect(c, a, 2.0)
I = Intersect(c, a, 1.0)
j = Segment(I, H)
J = Intersect(c, j, 2.0)
k = CircleArc(O, J, D)
T7: k + ""
l = Segment(A, O)
g = Segment(O, A)
m = Segment(A, D)
T10: i + ""
T11: "cos(" + RadianAlpha + ") = " + (y(D_1))