Angles, periods and reference angles
Angles, periods and reference angles

In AS questions, trigonometric equations are usually solved in degrees, so check your calculator is in degree mode first. The unit circle shows why one trig value can match more than one angle in a full turn.
Step-by-step lessons on Edexcel AS Level Maths Trigonometric Identities and Equations, covering 10.1 Angles in all four Quadrants, 10.2 Exact Values of Trigonometric Ratios, 10.3 Trigonometric Identities, 10.4 Solving Trigonometric Equations, 10.5 Harder Trigonometric Equations, and 10.6 Equations and Identities. Each one builds up to exam-style questions. Build fluency in the core algebra, surds and trigonometry topics early, since they underpin the calculus, statistics and mechanics content that follows.