# Trigonometry

### From DT Online

Trigonometric ratios are used to calculate angles and lengths of sides of triangles. Most commonly, the ratios relate to a right-angled triangle and are known as the **Sine**, **Cosine**, or **Tangent** of a given angle.

**Trigonometry** also exists for non-right-angled triangles but since a non-right-angle triangle can be bisected to create two right-angle triangles, most problems can be reduced to calculations on right-angle triangles.

An exception is the **Sine Rule** shown opposite which can be very helpful when determining the unknown forces in a **Force Triangle** for example.