Create a circle with radius 1 centered on the origin.

1. Create a circle with radius 1 centered on the origin (you should have two points A(0,0) and B(1,0)).
2. Create your initial ray by constructing a vector from A to B. Right click on the vector, and change it's label to "Initial".
3. Create a slider using the slider tool, and choose "angle". The label on your slider should read "=45".
4. Now create an angle to use the value from your slider. Use the "angle with given size" tool. Click on B, then A, then the definition will pop up. Change 45° to . This should create an angle that is controlled by your slider, and a new point B' on your circle. Test your slider to see the angle change.
5. Create a new vector from A to B' called "Terminal".
6. Drop a perpendicular line from B' to the x-axis. Mark the intersection of this line with a point (should be point C).
7. Draw reference triangle AB'C using the polygon tool. Remove the labels for sides, and show the label for the shape. Change its name to "Reference".

Challenge task

By now, your unit circle should look something like the one below. See if you can figure out how to display the values of sine and cosine like I did below.