The torque τ \tau\,τ in a precision galvanometer is given by the interaction of two magnetic fields. For the system to be in equilibrium at an angle α\alphaα, the following condition must be met:
5cosα+3=4sinαtanα 5\cos \alpha + 3 = 4\sin \alpha \tan \alpha 5cosα+3=4sinαtanαShow that this condition can be rewritten as the quadratic equation
9cos2α+3cosα−4=0 9\cos^2 \alpha + 3\cos \alpha - 4 = 0 9cos2α+3cosα−4=0A specific test run observes the system over the time interval 0≤t<π0 \le t < \pi0≤t<π, where the angle is driven such that α=2t\alpha = 2tα=2t. Determine the times t t\,t at which 5cos(2t)+3=4sin(2t)tan(2t)5\cos(2t) + 3 = 4\sin(2t) \tan(2t)5cos(2t)+3=4sin(2t)tan(2t), giving your answers to 2 decimal places.
317 exam-style questions on OCR A Level Maths 1.5 Trigonometry, covering 1.5.1 Definitions for all arguments, 1.5.2 Sine and cosine rules, 1.5.3 Area of a triangle, 1.5.4 Radian measure (A-level only), 1.5.5 Small angle approximations (A-level only), 1.5.6 Graphs of basic trigonometric functions, 1.5.7 Exact values in radians (A-level only), 1.5.8 Reciprocal and inverse trigonometric ratios (A-level only), 1.5.9 Graphs of reciprocal and inverse functions (A-level only), 1.5.10 Trigonometric identities, 1.5.11 Further trigonometric identities (A-level only), 1.5.12 Double angle and compound angle formulae (A-level only), 1.5.13 Geometrical proofs of formulae (A-level only), 1.5.14 Harmonic form Rcos / Rsin (A-level only), 1.5.15 Trigonometric equations, 1.5.16 Proof involving trigonometric functions (A-level only), and 1.5.17 Trigonometric functions in context. Each one has a worked solution and a mark scheme showing where the marks go.