AQA A Level Maths: Pure复习笔记5.8.1 Trigonometric Proof

Trigonometric Proof

Proving trigonometric identities

  • You can use trigonometric identities you already know to prove new identities
  • Make sure you know the simple trigonometric identities and further trigonometric identities
  • To prove an identity start on one side and proceed step by step until you get to the other side

5.8.1-Trig-Proof-Illustr-1

  • Clever substitution into the compound angle formulae can be a useful tool for proving identities

5.8.1-Trig-Proof-Illustr-2

  • Make sure you are confident handling fractions and fractions-within-fractions

5.8.1-Trig-Proof-Illustr-3

  • Always keep an eye on the 'target' expression – this can help suggest what identities to use

Exam Tip

  • Don't forget that you can start a proof from either end – sometimes it might be easier to start from the right-hand side (see the Worked Example)
  • A number of trigonometric identities are given to you in the formulae booklet – make sure you know which ones are (and aren't) in there

Worked Example

5.8.1-Trig-Proof-Example

 

 

 

 

 

 

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