Ch 9: Trigonometric Ratios

About This Chapter

Get ready for an important exam or a homework assignment with this engaging chapter on trigonometric ratios. Our mobile-friendly video and text lessons allow you to work at your own pace as you're learning all the subjects you need to get the best score possible.

Trigonometric Ratios - Chapter Summary

In this informative chapter, our professional instructors present trigonometric ratios. Our lessons cover the sine and cosine functions in trigonometry, as well as the equations associated with circular functions. Other topics covered in this fun chapter include using compass bearings to solve real world problems and relating right triangles to cosine and sine using unit circles. You'll also review how to apply the difference and sum identities. This chapter is designed to help you:

  • Use angles of elevation and depression to solve problems
  • Find the area of a triangle using sine
  • Understand the formula associated with half angle
  • Explain the basic trigonometric identities

Our short video and text lessons cover all the important topics you need to know to get caught up in class or study for a test. If you have questions as you work through the chapter, you're welcome to reach out to one of our instructors. It's easy to go back or jump forward to a specific section of a video lesson using the video tabs feature. You can access these tools 24 hours a day on your mobile device or computer for fast, convenient studying.

9 Lessons in Chapter 9: Trigonometric Ratios
Test your knowledge with a 30-question chapter practice test
Trigonometry: Sine and Cosine

1. Trigonometry: Sine and Cosine

Learn an easy trick to help you solve trigonometry problems, including problems with sine, cosine and inverse trig functions. At the end of this lesson, you'll know what SohCahToa means and how to use it.

Circular Functions: Equations & Examples

2. Circular Functions: Equations & Examples

In this lesson, we will learn how to define the basic trigonometric functions using a circle. In doing so, every angle in a circle will be paired with an ordered (x,y) point in the coordinate plane using the basic trigonometric functions.

Solving Real World Problems With Compass Bearings

3. Solving Real World Problems With Compass Bearings

There are several methods to indicate which way an object is heading by using a compass. In this lesson, we will focus on three figure compass bearings to solve real world problems.

Problem-Solving with Angles of Elevation & Depression

4. Problem-Solving with Angles of Elevation & Depression

In this lesson, you'll explore the difference between angles of elevation and depression. You'll also learn how to solve problems related to angles of elevation and depression using basic trigonometric relationships

Using Unit Circles to Relate Right Triangles to Sine & Cosine

5. Using Unit Circles to Relate Right Triangles to Sine & Cosine

The unit circle is a helpful tool for understanding trigonometric concepts. In this lesson, we'll look at right triangles on the unit circle to better grasp sine and cosine.

Using Sine to Find the Area of a Triangle

6. Using Sine to Find the Area of a Triangle

Since you first started working with triangles in math class, chances are you've been exposed to the formula for the area of a triangle. However, that is only good if you know the height of the triangle. This lesson shows you how to get around that.

Applying the Sum & Difference Identities

7. Applying the Sum & Difference Identities

Watch this video lesson to learn the six sum and difference identities for the trig functions of sine, cosine, and tangent. Also, learn how you can use them to your advantage when solving tough trig problems.

Half Angle: Rule, Formula & Examples

8. Half Angle: Rule, Formula & Examples

If we know at least the cosine of an angle, we can use formulas to find the sine, cosine and tangent of half that angle. These formulas are called half-angle formulas. In this lesson we state half-angle formulas, describe the rules for using them, and present examples.

List of the Basic Trig Identities

9. List of the Basic Trig Identities

There are specific trig functions that have very special and very simple relationships with each other. Learn the main one and how you can use it to understand the others.

Chapter Practice Exam
Test your knowledge of this chapter with a 30 question practice chapter exam.
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Practice Final Exam
Test your knowledge of the entire course with a 50 question practice final exam.
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