# Topic 1.2 The Unit Circle – Part I

The *Unit Circle – Part I* establishes the connection between angles measured counterclockwise from the positive side of the *x*-axis and points on a circle of radius 1 and formalizes this as a function from angles to points (ordered pairs). From this, the *sin* and *cos* functions are defined. Value of sin and cos are found for angles which are multiples of 90°. Values which come from the 30° – 60° – 90° triangle and the 45° – 45° – 90° triangle are presented in the *Unit Circle – Part II* lesson.

Slideshow: Full – 4 per page – 9 per page