Cosine Rule

Introduction

The Cosine Rule is given by the formula:


a2 = b2 + c2 – 2 bc cosA

This formula can also be expressed in the form:

Explore!

Use the applet below to explore the proof of the Cosine Rule.

Click on Animate to begin.

Test Yourself!

Use the applet below to test your understanding of cosine rule.

Next: Let's apply what we have learnt in bearings.