The
purpose of this applet is to illustrate the relation between the unit
circle and how the trigonometric functions are defined. Use it as
follows:

Drag the point
around the unit circle, clockwise or counterclockwise, as many times
as you want. As you do so, the following should happen:

- The coordinates
of the point will be updated.
- The point will
be in green if it corresponds to a positive angle, otherwise it
will be red.
- Depending on
which trigonometric function you have chosen (sine or cosine), its
graph will appear and the point on the unit circle will also appear
on the graph of the trigonometric function.
- A red line
whose length is the value of the chosen trigonometric function will
be displayed on both the unit circle and the graph.
- If the box
"Show Function Values" is checked, the the angle and the value of
the chosen trigonometric function at that angle will be displayed.
- As the point
on the graph gets ready to leave the graph, the graph will scroll
left or right, so that the point remains visible.