Strategy for Further Trigonometric Equations (Edexcel International A Level Maths: Pure 3)

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Strategy for Further Trigonometric Equations

How to approach solving harder trig equations

  • You can solve harder trig equations, such as those involving reciprocal and inverse functions in a variety of different ways
    • Using further trigonometric identities
    • Using compound or double angle formulas
    • Factorising quadratic trig equations
    • Then finding all solutions using CAST or sketching graphs
  • The final rearranged equation you solve will involve sin, cos or tan – don’t try to solve an equation with cosec, sec, or cot directly
  • If you’re having trouble solving a trig equation, this flowchart might help:

Strategy for Further Trigonometric Equations Diagram 1, A Level & AS Maths: Pure revision notes

Examiner Tip

  • Try to use identities and formulas to reduce the equation into its simplest terms.
  • Don’t forget to check the function range and ensure you have included all possible solutions.
  • If the question involves a function of x or θ ensure you transform the range first (and ensure you transform your solutions back again at the end!).

Worked example

Strat for Further Trig Eqns Example, A Level & AS Maths: Pure revision notes

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Roger

Author: Roger

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.