Math 20-2

Chapter 3 Acute Triangle Trigonometry

Lesson 3.2 Proving and Applying the Sine Law

GOAL

The goal of this lesson is stated at the top of page 132 in your textbook, and is also written below.
Keep this in mind as you work through the lesson material.

Explain the steps used to prove the sine law. Use the law to solve triangles.

Explore...

Try to answer the question in the sidebar on page 132

Watch

Video Tutorial

Investigate the Math

Investigate an idea or problem, with a partner if possible.
The investigation provides the background for the ideas presented in the lesson.

TEXT Pages 132 - 133

Read/Work through the Investigate section on Pages 132-133 in your textbook.

Go through this material,  AS BEST YOU CAN,  before you view the video tutorials that follow.

Introduction

Do your best to follow along with Ben’s proof.   
It’s fine, just maybe needs a bit more detail.
I will go through all the questions (A - I) in the video below.

?  How can you improve Ben’s explanation of his proof?

Be sure to work through the investigation as best as you can, before you watch the video!!
I’ve done my best to answer all the questions in the video below

Video Tutorial

Apply the Math  (Examples)

Examples will give you TOOLS for solving problems, and also show you that there may be different ways to approach a question.

YOUR TURN gives YOU the chance to try to do a problem ON YOUR OWN,  using the examples as models.

Example 1  Using reasoning to determine the length of a side

TEXT Page 134

Work through Example 1 on Page 134 in your textbook.

Watch

Video Tutorial

Your Turn

Use the Video Tutorial for help, or to check your work, BUT... you should do your best to do this question ON YOUR OWN FIRST!

Video Tutorial

Example 2  Solving a problem using the sine law

TEXT Page 135

Work through Example 2 on Page 135  in your textbook.

Watch

Video Tutorial

Your Turn   (there isn’t one for this example)

Example 3  Using reasoning to determine the measure of an angle

TEXT Pages 136 - 137

Work through Example 3 on Pages 136 - 137 in your textbook.

Watch

Video Tutorial

Your Turn

Use the Video Tutorial for help, or to check your work, BUT... you should do your best to do this question ON YOUR OWN FIRST!

Video Tutorial

In Summary

Key Ideas and Need to Know 
Presents and summarizes  the main new concepts of the lesson

•	Carefully read through each of the bullet points in this section.

•	If you are unclear about any of these ideas,  ASK YOUR TEACHER FOR HELP!

Practice Problems

Doing Practice Problems

Practice problems reinforce the math presented in this lesson.

•	Work through the practice problems for this lesson.
	These problems are for practice, you don’t need to hand them in!
	(your teacher may assign specific questions for you to complete)

•	Use the answers in the back of the book to CHECK YOUR WORK!

•	If you make a mistake, TRY TO FIX IT!

•	If you need help or want more information, view the video solutions provided.

•	If you still need more help,  CONTACT YOUR TEACHER!

Types of Practice Problems

Check Your Understanding questions require basic understanding of the ideas of the  lesson.

Practising questions will require you to dig deeper for a solution.

Closing  A summary question that often asks YOU to explain ideas in your own words.

Extending questions offer enrichment and extension.

Notes

Question 14,    I didn’t do a video for this one.
If you know two angles  and a side, that would work.
If you had an angle,  and two sides but neither was opposite that angle,  that wouldn’t work.

Question 16,    I didn’t do a video for this one.
A great question, and if you have a classmate you can work with, explain things to, that would be helpful.
“Teaching” someone is an excellent way to learn!
I didn’t do a video since I feel like I’ve kind of covered this multiple times already in the other questions.

Video Solution Links

Check your work for every problem you do!
If you make a mistake,  try to fix it!
Use the video solutions for more information.
If a problem still doesn’t make sense, ASK YOUR TEACHER FOR HELP!

({{"Question 1", "Question 2", "Question 3", "Question 4", "Question 5"}, {"Question 6", "Question 7", "Question 8", "Question 9", "Question 10"}, {"Question 11", "Question 12", "Question 13",  , "Question 15"}, { , "Question 17", "Question 18", "Question 19", }})