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ASMaths: PureAQARevision Notes5. Trigonometry5.3 Trigonometric Equations5.3.1 Trigonometry - Simple Identities

Trigonometry - Simple Identities (AQA AS Maths: Pure)

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Trigonometry - Simple Identities

What is a trigonometric identity?

  • Trigonometric identities are statements that are true for all values of x or theta (θ)
  • They are used to help simplify trig equations before solving them
  • The first two identities you must know are:

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

Where do these identities come from?

  • Although you don’t need to know the proof for these identities it is important to understand where they come from

Trigonometry - Simple Identities Diagram 2a, A Level & AS Level Pure Maths Revision Notes  Trigonometry - Simple Identities Diagram 2b, A Level & AS Level Pure Maths Revision Notes

How to use the identities

Trigonometry - Simple Identities Diagram 3, A Level & AS Level Pure Maths Revision Notes

Examiner Tip

  • You’ll need to remember these identities as they aren’t in the formula booklet.
  • If asked to show one thing is identical (≡) another look at what parts are missing –  for example, if tan x has gone it must have been substituted.

Worked example

Trigonometry - Simple Identities Example Answer, A Level & AS Level Pure Maths Revision Notes

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    Lucy

    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.