Focus

Math 10C Module 1 Lesson 7

Module 1 Part 2: Trigonometry

 

Lesson 9: Using Trigonometry to Find Missing Angles

 ** Always have your calculator in degree mode. Check by hitting the MODE button and looking at the third line. The word degree must be darkened**

Focus

 Over 2000 years ago, Eratosthenes of Cyrene (c. 276 BCE–195 BCE) used trigonometry to estimate the diameter of Earth. Today’s accepted value is approximately 40 000 km. His value was between 39 690 km and 46 620 km—not a bad calculation from someone who was working without a calculator, satellite imagery, laser range-finder, or even algebraic symbols!


 Trigonometry is the study of triangles, including the relationships between side lengths and angles. So far in this module, you have learned how to define sine, cosine and tangent and then how to use these concepts to find missing sides.
In this lesson, you will use sine, cosine and tangent to find missing angles in a right triangle.

 

Outcomes

 

At the end of this lesson, you will be able to find missing angles in a right triangle. This will involve:

  • the use of sin, cos and tan to develop a statemtn.
  • the use of the SIN-1, COS-1 and TAN-1 buttons on your calculator.

Lesson Questions

 

By the end of this lesson, you should feel comfortable solving the following questions:

  • In what situations can the concepts of trigonometry be used to solve problems?

  • How do I use sine, cosine, and tangent ratios and my calculator to find missing angles in right triangles?
Lesson Completion and Assessment

 

As you work through each lesson, complete all the questions and learning activities in your binder using paper and pencil, clearly labeling your work (they refer to this as your course folder). These include the Are you Ready, Try This, Share and Self Check questions. Check your work if answers are provided. Remember that these questions provide you with the practice and feedback that you need to successfully complete this course.
Once you have completed all of the learning activities, take the Lesson Quiz. This is the assessment for each lesson and is located under the Assess tab or by using the Quizzes link under the Activities block.


** Note – Share questions may have to be done on your own depending on your learning situation**

Â