A LevelMaths: PureOCRRevision Notes5. Trigonometry5.1 Basic Trigonometry5.1.1 Trigonometry - Definitions

Trigonometry - Definitions (OCR A Level Maths: Pure)

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Lucy

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4 August 2023

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Trigonometry - Definitions

What is trigonometry?

Trigonometry looks at the relationship between side lengths and angles of triangles
It comes from the Greek words trigonon meaning ‘triangle’ and metron meaning ‘measure’
The three trigonometric functions Sine, Cosine and Tangent come from ratios of side lengths in right angled triangles

Trigonometry - Definitions Diagram 1, A Level & AS Level Pure Maths Revision Notes

What is the unit circle and how does it help with trigonometry?

The unit circle is a circle with radius 1 and centre (0, 0)
It can be used to calculate trig values as a co‑ordinate point (x, y) on the circle
(x, y) = (cos θ, sin θ), where θ is the angle measured anticlockwise from the positive x‑axis
It allows us to calculate sin, cos and tan for angles greater than 90°

Trigonometry - Definitions Diagram 2, A Level & AS Level Pure Maths Revision Notes

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Trigonometry - Definitions Example Question, A Level & AS Level Pure Maths Revision Notes

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Author: Lucy

Expertise: Head of STEM

Lucy has been a passionate Maths teacher for over 12 years, teaching maths across the UK and abroad helping to engage, interest and develop confidence in the subject at all levels. Working as a Head of Department and then Director of Maths, Lucy has advised schools and academy trusts in both Scotland and the East Midlands, where her role was to support and coach teachers to improve Maths teaching for all. Lucy has created revision content for a variety of domestic and international Exam Boards including Edexcel, AQA, OCR, CIE and IB.