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1.5.16 Proof involving trigonometric functions (A-level only)

Card 1 of 21

Why is sin⁡x=cos⁡x\sin x=\cos xsinx=cosx an equation rather than an identity?

A

cos⁡x≠0\cos x\neq0cosx=0

B

It is true only for particular values of xxx.

C

The cosine compound-angle identity is cos⁡(A±B)≡cos⁡Acos⁡B∓sin⁡Asin⁡B\boxed{\cos(A\pm B)\equiv\cos A\cos B\mp\sin A\sin B}cos(A±B)≡cosAcosB∓sinAsinB​.

D

It avoids assuming the identity or hiding an irreversible step.

Card 1 of 21

1.5.16 Proof involving trigonometric functions (A-level only) Flashcards

  1. A Level
  2. /Maths
  3. /1.5.16 Proof involving trigonometric functions (A-level only)

21 flashcards on OCR A Level Maths 1.5.16 Proof involving trigonometric functions (A-level only): the key formulae, methods and definitions you need to recall for Paper 1, Paper 2 and Paper 3.

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