# The Cosine Rule

> This section finds a missing side or a missing angle in any triangle with the cosine rule: a^2=b^2+c^2-2bccos A (and cyclic). Use two sides and the included angle (SAS) to find the third side, or…

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## More in Trigonometry: Sine, Cosine and Area Rules

- [The Sine Rule](https://www.hlayiso.com/grade-12/mathematics/notes/trigonometry-sine-cosine-and-area-rules/the-sine-rule) — Previous section
- [Solving Problems in Two and Three Dimensions](https://www.hlayiso.com/grade-12/mathematics/notes/trigonometry-sine-cosine-and-area-rules/solving-problems-in-two-and-three-dimensions) — Next section
- [All Trigonometry: Sine, Cosine and Area Rules sections](https://www.hlayiso.com/grade-12/mathematics/notes/trigonometry-sine-cosine-and-area-rules)

## Frequently asked questions

### What will I learn in "The Cosine Rule"?

This section covers The Cosine Rule as part of Trigonometry: Sine, Cosine and Area Rules in Grade 12 Mathematics. You'll find clear explanations, worked examples, and key definitions aligned to the CAPS curriculum.

### Is this section aligned with the CAPS curriculum?

Yes. All notes on Hlayiso, including "The Cosine Rule", are written against the official CAPS curriculum and ATP for Grade 12 Mathematics.

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Continue with the next section in Trigonometry: Sine, Cosine and Area Rules, or test your understanding with the interactive quiz linked to this section.

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