Strategy for Trigonometric Equations (Edexcel AS Maths) : Revision Note
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Strategy for Trigonometric Equations
How to approach solving trig equations
You can solve trig equations in a variety of different ways
Sketching a graph (see Graphs of Trigonometric Functions)
Using trigonometric identities (see Trigonometry – Simple Identities)
Using the CAST diagram (see Linear Trigonometric Equations)
Factorising quadratic trig equations (see Quadratic Trigonometric Equations)
If you’re having trouble solving a trig equation, this flowchart might help:

Examiner Tips and Tricks
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, make sure you transform the range first (and ensure you transform your solutions back again at the end!).
Worked Example

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