Revision NotesExam QuestionsPast Papers
A LevelMathsOCRMaths APureRevision NotesTrigonometryCompound & Double Angle FormulaeDouble Angle Formulae

Double Angle Formulae (OCR A Level Maths A) : Revision Note

Roger B

Author

Roger B

Last updated

OCR Maths A: PureAQA Maths: PureEdexcel Maths: Pure

Did this video help you?

Double Angle Formulae

What are the double angle formulae?

  • The double angle formulae are derived from the 'A+B' versions of the compound angle formulae:

    • sin open parentheses 2 A close parentheses identical to 2 sin A cos A

    • cos left parenthesis 2 A right parenthesis identical to cos squared A minus sin squared A

      • cos left parenthesis 2 A right parenthesis identical to 2 cos squared A minus 1

      • cos left parenthesis 2 A right parenthesis identical to 1 minus 2 sin squared A

    • tan left parenthesis 2 A right parenthesis identical to fraction numerator 2 tan A over denominator 1 minus tan squared A end fraction

Double Angle Forms Illustr 1_sin, A Level & AS Maths: Pure revision notes

 

Double Angle Forms Illustr 2_cos, A Level & AS Maths: Pure revision notes

 

Double Angle Forms Illustr 3_tan, A Level & AS Maths: Pure revision notes

Examiner Tips and Tricks

  • The double angle formulae are not included in the formulae booklet – you have to know them.

  • If you forget them, you can always derive them from the compound angle formulae (which are in the formula booklet) as shown above.

Worked Example

Double Angle Forms Example, A Level & AS Maths: Pure revision notes

You've read 0 of your 5 free revision notes this week

Sign up now. It’s free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

    Test yourself

    Did this page help you?

    Previous:Compound Angle FormulaeNext:Harmonic Form
    Roger B

    Author: Roger B

    Expertise: Maths

    Roger's teaching experience stretches all the way back to 1992, and in that time he has taught students at all levels between Year 7 and university undergraduate. Having conducted and published postgraduate research into the mathematical theory behind quantum computing, he is more than confident in dealing with mathematics at any level the exam boards might throw at you.