More on the Laws: Real World Application

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SWBAT use the Law of Sines and the Law of Cosines to solve oblique triangles.

Big Idea

Student teams race to solve challenging oblique triangle problems in context.

Quick Intro

2 minutes

Before the activity, I will briefly teach my students how to interpret the bearing directions given in these problems. For example, S 23 E means start out going due south and then turn 23 degrees in the east direction and head east. This video does a good job explaining how to understand and apply bearing directions:

Source Url: (Accessed June 25, 2014)

I will only show the video until about the 2:00 mark. But, there are example problems after this point that might help my students so I will share the link for the video with my class for them to review on their own.


Let the Games Begin

48 minutes

First, each team should receive one set of the laminated problem cards (Law of Sines and Cosines Word Problems) in a unique color.** Students can work on any problem they would like. I will be providing whiteboards and markers for students to do their work on.  Once students think they have the correct answer they should write the answer with a dry erase marker on the laminated problem card and turn it in. As students turn in these cards, I will check the answers and return cards that are incorrect. If teams are repeatedly getting incorrect answers, then I can address the issues with the team. For this reason, I am going to ask students to keep one person’s work until they know their answers are correct.

The different colors for each team will help us to distinguish which team the cards belong to and really will make this activity smoother. I will be able to just call out things like “blue team, all of your answers are correct.” It will also help to identify teams that are struggling since we won’t have any papers that color.  However, the colors are not required, it really just makes things go smoother. Students could of course just write their names on the cards too.

I will then keep all correct cards and return incorrect cards. The team that has the most correct will win something (extra credit, candy, free homework pass to not complete #8… maybe all of the above!).

** Special Preparation Note: When copying these word problems, Law of Sines and Cosines Word Problems, I am going to make a different colored set for each team in the class. Then I am going to cut apart the problems and have each card laminated. This will help to facilitate the activity that we will do in class. Individual student whiteboards and markers will also be needed for today’s lesson.



The assignment for tonight is Homework 8 - Fundamentals of Trigonometry.