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Trigonometry and Modelling

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Question 101
a.

Using the identity cos⁡2x=1−2sin⁡2x\cos 2x=1-2\sin^2 xcos2x=1−2sin2x, show that

cos⁡2x−7sin⁡x+3=0 \cos 2x-7\sin x+3=0 cos2x−7sinx+3=0

can be written as

2sin⁡2x+7sin⁡x−4=0 2\sin^2 x+7\sin x-4=0 2sin2x+7sinx−4=0
[2]
b.

Hence solve, for −180≤x≤180-180 \leq x \leq 180−180≤x≤180, the equation,

cos⁡2x−7sin⁡x+3=0 \cos 2x-7\sin x+3=0 cos2x−7sinx+3=0
[3]
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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