Reason For Learning
When you work with angles in all four quadrants, the trig ratios for those angles are computed in terms of the values of x, y, and r, where r is the radius of the circle that corresponds to the hypotenuse of the right triangle for your angle.
Leads to higher math levels.
Learning Intention
That the "Unit Circle" is just a circle with a radius of 1. How to place a point on x and y axes in a unit circle. How to use radians instead of angles. How to work with angles in all four quadrants.
Key Vocabulary Terms