Intervals, periods and reference angles
Intervals, periods and reference angles

Trigonometric equations repeat, so the interval tells you how many solutions to look for. Before using inverse trig, check whether the question is in degrees or radians and match your calculator mode.
Step-by-step lessons on Edexcel A Level Maths Trigonometry and Modelling, covering 7.1 Addition Formulae, 7.2 Double Angle Formulae, 7.3 Solving Trigonometric Equations, 7.4 Simplifying a cos x +- b sin x, 7.5 Proving Trigonometric Identities, and 7.6 Modelling with Trigonometric Functions. Each one builds up to exam-style questions. Build fluency with the core pure algebra and calculus toolkit early, since almost every mechanics and statistics topic on the course depends on it.