Move the point on the circle in the left window (Graphics 1).
This applet demonstrates how to use Graphics 2 of GeoGebra. Graphics 1 shows the distances on the circle: distance traveled (a) by a point about the circle from (1,0), it's distance from the x-axis (b), and its distance from the y-axis (c).
Graphics 2 shows the two points with coordinates (a,b) and (a,c). The traces of the points in Graphics 2 forms the graph of the sine function and the consine function from 0 to pi.
Download GGB file.