**CHAPTER 3, SECTION B:** *THE UNIT CIRCLE PICTURE
FOR THE SINE AND COSINE
*

- the idea and geometrical meaning of angles and angular measure (reviewable by reading (or re-reading) the various sections of Chapter 1 of the course, which can be accessed by clicking HERE),
- the basic geometrical definitions of all six trig functions as the ratios of sides of the appropriate right angle triangles, phrased in terms of the concepts "hypoteneuse", "adjacent" and "opposite" (reviewable by reading (or re-reading) Section (c) of Chapter 2 of the course) and
- the algebraic relations amongst the various trig functions of the same angle, especially those which allow the tangent, cotangent, secant and cosecant to be written in terms of the sine and cosine (reviewable by reading (or re-reading) the previous section, Section (a), of Chapter 3 of this course)

**OVERVIEW:**

This section of Chapter 3 introduces the "unit circle picture" for visualizing the sine and cosine functions. This picture will be especially important in the next section (Section (c)) of Chapter 3 where we will use it to help us to figure out how to generalize all six of the trig functions to angles corresponding to non-first quadrant directions.

A list of the background material needed to follow the contents of this section is given below. If you are unfamiliar with one of the background topics, or feel you would like to quickly review it, click on the relevant link.

**If you are already familar with all of the background material,
you can proceed directly to the contents of the current section
of the course by clicking HERE.
**

**BACKGROUND MATERIAL (AND LINKS):**

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For this section of the course, you should be familiar with*