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Lesson 7

1. Lesson 7

1.8. Lesson 7 Summary

Mathematics 30-3 Module 5

Module 5: Geometry

 

Lesson 7 Summary

 

This diagram shows a triangle with sides a, b, and c. The angle across from side a is labelled “A.”

In this lesson you explored the cosine law. The cosine law is useful when you are given three sides of a triangle or two sides and the angle between them. Just as in the sine law, the cosine law can be used with any triangle. To determine an unknown side, the equation a2 = b2 + c2 − 2bc cos A can be used. To determine an unknown angle, the equation can be used.