 ## Trigonometry

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### T1 Pythagoras’ theorem

Pythagoras’ Theorem shows the relationship between the sides of a right-angled triangle. Knowing the length of two sides of a right-angled triangle, the length of the third side can be calculated.

### T2 Right triangle trigonometry

Trigonometry is a branch of mathematics that has applications across many fields of science and engineering. This module shows how to apply trigonometric ratios within right-angled triangles.

### T3 The sine rule

How can we apply trigonometry to triangles that do not possess a right-angle? The sine rule shows that the ratio of the length of a side to the sine of its opposite angle will be the same for all...

### T4 Cosine rule

The cosine rule is a generalisation of Pythagoras’ theorem. Given any two sides of a triangle, as long as we know the angle between them, we can calculate the length of the third side.

### T5 Angular measurement and the unit circle

Angles are frequently measured in degrees. However, it is sometimes useful to define angles in terms of the length around the circle. This module introduces radians as a measure of angle.

### Trigonometry

Trigonometry is a branch of mathematics involving the study of triangles, and has applications in fields such as engineering, surveying, navigation, optics, and electronics.