Revise trigonometric ratios of sine, cosine and tangent and calculate angles in right-angled triangles with this BBC Bitesize GCSE Maths OCR study guide.

The three trigonometric ratios; sine, cosine and tangent are used to calculate angles and lengths in right-angled triangles. The sine and cosine rules calculate lengths and angles in any triangle.

This means that any complex calculation using classical trigonometry could result in a significant accumulation of errors.