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Trigonometry and Modelling

Trigonometry and Modelling

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Question 9
a.

By writing cos⁡3x \cos 3x\,cos3x as cos⁡(2x+x)\cos(2x + x)cos(2x+x), show that cos⁡3x=4cos⁡3x−3cos⁡x\cos 3x = 4\cos^3 x - 3\cos xcos3x=4cos3x−3cosx

[2]
b.

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

4cos⁡3x−3cos⁡x=32 4\cos^3 x - 3\cos x = \frac{\sqrt{3}}{2} 4cos3x−3cosx=23​​

Give your answers in terms of π\piπ.

[4]
Markscheme

Trigonometry and Modelling Questions

  1. A Level
  2. /Maths
  3. /Trigonometry and Modelling

137 exam-style questions on Edexcel A Level Maths Trigonometry and Modelling, covering 7.1 Addition Formulae, 7.2 Double Angle Formulae, 7.3 Solving Trigonometric Equations, 7.4 Simplifying a cos x +- b sin x, 7.5 Proving Trigonometric Identities, and 7.6 Modelling with Trigonometric Functions. Each one has a worked solution and a mark scheme showing where the marks go.

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