The connection ‘tween sine and cosine.

Question

The message this animation wants to convey seems to be of particular significance, but what is it trying to explain actually? I looked at it for hours, but I just don't get it!

Answer 1

I believe that what this image intends to represent is the following:

If you were spinning around a circle in constant speed(both angular and otherwise). then your $x$ coordinate is $x(t)=c_0\cdot cos(t)$, and your y coordinate is $y(t)=c_0\cdot sin(t)$

So the image is showing that if you combine the $cos(t)$ and $sin(t)$ graph you would always obtain the curve $(cos(t)$,$sin(t))$ which is nothing more than a circle