Sketch a unit circle. In your unit circle, sketch an angle that has:   

1. A positive cosine and a negative sine.

2. A sine of $–1$.

3. A negative cosine and a negative sine.

4. A cosine of approximately $–0.9$ and a sine of approximately $0.4$.

5. Can an angle have a sine of $0.9$ and cosine of $0.8$? Give an example or explain why not.
   

   Use the eTool below to explore these ideas.
   Click the link at right for the full version of the eTool: INT3 9-53 HW eTool