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Trigonometry and Modelling

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Question 175
a.

Show that

sin⁡3x≡3sin⁡x−4sin⁡3x \sin 3x \equiv 3 \sin x - 4 \sin^3 x sin3x≡3sinx−4sin3x
[4]
b.

Hence, verify that, for 0≤x<π0 \leq x < \pi0≤x<π,

8sin⁡3x−6sin⁡x=0 8 \sin^3 x - 6 \sin x = 0 8sin3x−6sinx=0

has solutions

x=0, π3, 2π3 x=0,\ \frac{\pi}{3},\ \frac{2\pi}{3} x=0, 3π​, 32π​
[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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