Based on your knowledge of the unit circle, see how sinusoids (sine and cosine waves) get their shapes.

Click the [b]Start/Stop[/b] button. Notice how both the green arc along the unit circle and the green line segment along the x-axis always maintain the same lengths. Therefore, the x-coordinate of point P also represents the radian measure of the arc's central angle.[br]This can also be viewed as "unwrapping" the arc and laying along the x-axis, starting from the origin.[br]Click the checkbox for either [b]sine[/b] or [b]cosine[/b] and once again observe how the geometry displayed on the unit circle is also represented sliding along the x-axis.[br]Click the [b]trace[/b] checkbox to view the formation of a sinusoid.