idcirc2.eps

Using the coordinates *a* and *b* for a given point on the unit
circle, we can find
the coordinates of some related points in the above figure.
Since and , we easily
get the sine and cosine of other angles, such as ,
, , ,
and .
You should be able to verify the following identities.

- .
- .
- .
- .
- .
- .
- .
- .
- .
- .

Wed Apr 21 08:17:28 EDT 1999