Module 7
1. Module 7
1.23. Lesson 5
Module 7: Trigonometry
Lesson 5: The Cosine Ratio
Focus
Clive Mason/Getty Images Sport/Getty Images
In the photograph, Mellisa Hollingsworth, from Eckville, Alberta, is shown competing in the women’s skeleton event at the 2006 Winter Olympics in Torino, Italy. She won a bronze medal at those games and a silver medal at the 2000 World Championships in Austria. In both the 2009-10 and 2005-06 seasons, she won the women’s World Cup overall skeleton title. Hollingsworth participated at the 2010 Vancouver Winter Olympics, where she finished in fifth place.
The 2010 Olympic bobsleigh and skeleton track at Whistler, British Columbia, is 1450 m in length with a vertical drop of 152 m and an average slope of 10.5°. In the Olympics women’s skeleton event, the combined mass of the competitor and sled cannot exceed 92 kg. Part of this combined weight pushes the runners against the track and part of the weight pushes the sled down the slope. On average, what percentage of the mass pushes the sled down the track? At the end of this lesson you will have the trigonometric skills to answer this question!
Lesson Questions
In this lesson you will explore these questions:
What is the cosine ratio?
How is the cosine ratio used to find unknown sides and angles in right triangles?
Assessment
You will complete the Lesson 5 Assignment Booklet for assessment. Download the Lesson 5 Assignment Booklet and save it in your course folder now. You will receive instructions on how to complete the Assignment Booklet later in the lesson. You will also be prompted to work on the Unit 3 Project.
Remember to save all of your work in your course folder.
Required Materials and Equipment
You will need a metric rule, your protractor, and a calculator.