This is a complete lesson on the cosine rule that looks at how to calculate unknown sides of triangles. The lesson is designed with the new GCSE specification in mind.

### Lesson Objectives

- To work out unknown sides using the cosine rule.
- To use the cosine rule to solve problems.

### Who is this Lesson For?

This pack is designed for GCSE higher tier students. It could also be used with high ability Key Stage 3 students.

### What is Included?

Included in this download are the following:

- Full lesson plan for the ‘Finding Sides Using the Cosine Rule’ lesson, including introduction, teaching content, individual activities, plenary and suggested support and extension activities
- Pythagoras’ Theorem Introduction
- Cosine Rule Demonstration Slide
- Finding a Side Using the Cosine Rule Example
- Mini-Plenary
- Student Worksheet on Finding Sides Using the Cosine Rule
- True or False Cards
- Further Trigonometry Fact Sheet
- Complete Solutions to all Questions

### Lesson Progression

This is the fourth lesson in the Further Trigonometry unit of work (the unit is also **available as a pack** including homework activities and a unit assessment).

The other lessons in the unit are: