Students learn how to derive and apply the Cosine Rule to find missing angles in triangles.

Later, as learning progresses students begin to calculate a combination of angles in adjoining triangles.

**Differentiated Learning Objectives**

- All students should be able to calculate an unknown angle in a triangle using the Cosine rule.
- Most students should be able to calculate an unknown angle or a bearing using the Cosine rule.
- Some students should be able to derive and apply the Cosine rule for triangular shapes.

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