Show that
cosθ(9tanθ+4tanθ)≡5sinθ+4sinθ \cos \theta \left( 9 \tan \theta + \frac{4}{\tan \theta} \right) \equiv 5 \sin \theta + \frac{4}{\sin \theta} cosθ(9tanθ+tanθ4)≡5sinθ+sinθ4for θ≠nπ2\theta \neq \frac{n\pi}{2}θ=2nπ, where nnn is an integer.
Hence solve, for 0<x<2π0 < x < 2\pi0<x<2π, the equation
cosx(9tanx+4tanx)=12sinx−2 \cos x \left( 9 \tan x + \frac{4}{\tan x} \right) = 12 \sin x - 2 cosx(9tanx+tanx4)=12sinx−2giving your answers to 3 significant figures.
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.