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Trigonometry and Modelling

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Question 6
a.

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

[4]
b.

Hence, solve, for −π2≤x≤π2\displaystyle -\frac{\pi}{2} \leq x \leq \frac{\pi}{2}−2π​≤x≤2π​,

1−cos⁡3x=83sin⁡2x 1 - \cos 3x = \frac{8}{3}\sin^2 x 1−cos3x=38​sin2x
[5]
Markscheme

Trigonometry and Modelling Questions

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

348 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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