By writing cos3x \cos 3x\,cos3x as cos(2x+x)\cos(2x + x)cos(2x+x), show that cos3x=4cos3x−3cosx\cos 3x = 4\cos^3 x - 3\cos xcos3x=4cos3x−3cosx
Solve, for 0≤x≤π0 \leq x \leq \pi0≤x≤π, the equation,
4cos3x−3cosx=32 4\cos^3 x - 3\cos x = \frac{\sqrt{3}}{2} 4cos3x−3cosx=23Give your answers in terms of π\piπ.
Practise AQA A Level Maths 1.8 E: Trigonometry with exam-style questions for A Level Maths. 239 questions covering 1.8.1 Trigonometric definitions, rules and radians, 1.8.2 Small angle approximations (A-level only), 1.8.3 Trigonometric functions and exact values, 1.8.4 Reciprocal and inverse trigonometric functions (A-level only), 1.8.5 Trigonometric identities, 1.8.6 Compound and double angle formulae (A-level only), 1.8.7 Solving trigonometric equations, 1.8.8 Proofs with trigonometric identities, and 1.8.9 Trigonometry in context, matched to the AQA A Level Maths (7357) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
