5.3.1

Sine Rules

Test yourself

Sine and Cosine Rules

We can use the sine and cosine rules to calculate angles and lengths in triangles.

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Labelling triangles

  • Use lowercase letters for the sides and capital letters for the angles opposite each side.
Illustrative background for Swapping A, B and CIllustrative background for Swapping A, B and C ?? "content

Swapping A, B and C

  • Note that the cosine rule can be written for the other angles too:
    • c2 = a2 + b2 - 2ab cos C
    • b2 = a2 + c2 - 2ac cos B

Jump to other topics

1Proof

2Algebra & Functions

2.1Powers & Roots

2.2Quadratic Equations

2.3Inequalities

2.4Polynomials

2.5Graphs

2.6Functions

2.7Transformation of Graphs

2.8Partial Fractions (A2 Only)

3Coordinate Geometry

4Sequences & Series

5Trigonometry

6Exponentials & Logarithms

7Differentiation

8Integration

9Numerical Methods

10Vectors

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