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Trigonometry and Modelling

Trigonometry and Modelling

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Question 55
a.

Given that cos⁡ϕ≠±1\cos \phi \neq \pm 1cosϕ=±1, prove the identity

11−cos⁡ϕ+11+cos⁡ϕ≡2csc⁡2ϕ \frac{1}{1 - \cos \phi} + \frac{1}{1 + \cos \phi} \equiv 2 \csc^2 \phi 1−cosϕ1​+1+cosϕ1​≡2csc2ϕ
[3]
b.

In a study of robotic arm resonance, the stability factor kkk is defined by the equation

11−cos⁡ϕ+11+cos⁡ϕ=k \frac{1}{1 - \cos \phi} + \frac{1}{1 + \cos \phi} = k 1−cosϕ1​+1+cosϕ1​=k

Determine the set of values of kkk for which this equation has real solutions for ϕ\phiϕ. Fully justify your answer.

[3]
c.

Given that ϕ\phiϕ is in the third quadrant (reflex angle between 180∘180^\circ180∘ and 270∘270^\circ270∘) and

11−cos⁡ϕ+11+cos⁡ϕ=18 \frac{1}{1 - \cos \phi} + \frac{1}{1 + \cos \phi} = 18 1−cosϕ1​+1+cosϕ1​=18

find the exact value of cot⁡ϕ\cot \phicotϕ.

[3]
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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