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3.5 Trigonometry (A-level only)

3.5 Trigonometry (A-level only)

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Question 77
a.

By writing cos⁡3θ \cos 3\theta\,cos3θ as cos⁡(2θ+θ)\cos(2\theta + \theta)cos(2θ+θ), show that

cos⁡3θ≡4cos⁡3θ−3cos⁡θ\cos 3\theta \equiv 4\cos^3\theta - 3\cos\thetacos3θ≡4cos3θ−3cosθ

[2]
b.

Solve, for 0≤θ≤π0 \leq \theta \leq \pi0≤θ≤π, the equation

4cos⁡3θ−3cos⁡θ=0.54\cos^3\theta - 3\cos\theta = 0.54cos3θ−3cosθ=0.5

Give your answers in terms of π\piπ.

[4]
Markscheme

3.5 Trigonometry (A-level only) Questions

  1. A Level
  2. /Maths
  3. /3.5 Trigonometry (A-level only)

225 exam-style questions on WJEC A Level Maths 3.5 Trigonometry (A-level only), covering 3.5.1 Trigonometry (A-level only), 3.5.2 Trigonometry (A-level only), 3.5.3 Trigonometry (A-level only), 3.5.4 Trigonometry (A-level only), 3.5.5 Trigonometry (A-level only), 3.5.6 Trigonometry (A-level only), 3.5.7 Trigonometry (A-level only), and 3.5.8 Trigonometry (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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