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1 Pure Mathematics

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Question 428
a.

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

[3]
b.

Hence solve, for −π≤x≤π-\pi \leq x \leq \pi−π≤x≤π, the equation

1−cos⁡3x=sin⁡2x1 - \cos 3x = \sin^2 x1−cos3x=sin2x

Give your answers to three significant figures where they are not exact.

[5]
Markscheme

1 Pure Mathematics Questions

  1. A Level
  2. /Maths
  3. /1 Pure Mathematics

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