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1.8 E: Trigonometry

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Question 42
a.

By writing cos⁡3ϕ \cos 3\phi\,cos3ϕ as cos⁡(2ϕ+ϕ)\cos(2\phi + \phi)cos(2ϕ+ϕ), show that cos⁡3ϕ=4cos⁡3ϕ−3cos⁡ϕ\cos 3\phi = 4\cos^3 \phi - 3\cos \phicos3ϕ=4cos3ϕ−3cosϕ.

[2]
b.

Solve, for 0≤ϕ≤1800 \leq \phi \leq 1800≤ϕ≤180, the equation,

12cos⁡3ϕ−9cos⁡ϕ=1.5 12\cos^3 \phi - 9\cos \phi = 1.5 12cos3ϕ−9cosϕ=1.5

Give your answers to 1 decimal place where necessary.

[4]
Markscheme

1.8 E: Trigonometry Questions

  1. A Level
  2. /Maths
  3. /1.8 E: Trigonometry

317 exam-style questions on AQA A Level Maths 1.8 E: Trigonometry, 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. Each one has a worked solution and a mark scheme showing where the marks go.

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