# The Unit Circle - and introduction investigation

- Author:
- John Fitzgerald

- Topic:
- Circle, Mathematics, Trigonometry, Unit Circle

This is an introduction to the unit circle.

1. What does angle alpha represent?
2. When could alpha be negative?
3. Can alpha be greater than 360?
4. What is the relationship between sin(alpha) and the y coordinate of A?
5. What is the relationship between cos(alpha) and the x coordinate of A?
6. In which quadrants is sin(alpha) positive?
7. In which quadrants is cos(alpha) positive?
In which quadrants is tan(alpha) positive?