you thought circles were simple? haha the green and red circles are the x and y values of the blue circle. they appear to be following two separate paths (gray lines), but also always stay a fixed distance apart (yellow line) and also seem to orbit around each other (inner gray circle). The red graph is the graph of the y position of the blue circle, and the green graph in the x position. These graphs may remind you of sine or cosine waves, and that's because they are the definition of sine and cosine waves. The yellow graph is the tangent function, which is sin/cos (or, in our case, y/x). For some reason this doesn't render correctly. all of this can be constructed from one dot orbiting around the origin.
