Trigonometry For Dummies, 2nd Edition

Chapter 4

Getting Your Degree

In This Chapter

Measuring angles in degrees

Putting angles in standard position

Finding many measures for the same angle

The main idea that distinguishes trigonometry from other mathematical topics is its attention to and dependence on angle measures. The trig functions (sine, cosine, tangent, cotangent, secant, and cosecant) are ratios based on the measures of an angle. What good are degrees (no, not the kind that tell you how hot or cold it is) in the real world? Navigators, carpenters, and astronomers can't do without them. How do you measure the degrees? You have many ways, dear reader, and I show you all you need to know in this chapter.

Angles, Angles Everywhere: Measuring in Degrees

What's a degree? When you graduate from college, you get your degree. The temperature outside went up a degree. When questioned, you get the third degree. All these scenarios use the word degree, but in trigonometry, a degree is a tiny slice of a circle. Imagine a pizza cut into 360 equal pieces (what a mess). Each little slice represents one degree. Look at Figure 4-1 to see what a degree looks like.

Figure 4-1: One degree is of a circle.

Slicing a coordinate ...