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7.5 Proving Trigonometric Identities

7.5 Proving Trigonometric Identities

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Question 9
a.

Show that

sin⁡2θsin⁡θ−cos⁡2θcos⁡θ≡sec⁡θ \frac{\sin 2\theta}{\sin \theta} - \frac{\cos 2\theta}{\cos \theta} \equiv \sec \theta sinθsin2θ​−cosθcos2θ​≡secθ

for θ≠nπ2\theta \neq \frac{n\pi}{2}θ=2nπ​ where n∈Zn \in \mathbb{Z}n∈Z.

[3]
b.

Solve, for 0∘≤x<45∘0^\circ \le x < 45^\circ0∘≤x<45∘, the equation

7cos⁡2(4x−10∘)=3 7 \cos^2(4x - 10^\circ) = 3 7cos2(4x−10∘)=3

giving your answers in degrees to one decimal place. (Solutions based entirely on graphical or numerical methods are not acceptable.)

[4]
Markscheme

7.5 Proving Trigonometric Identities Questions

  1. A Level
  2. /Maths
  3. /7.5 Proving Trigonometric Identities

26 exam-style questions on Edexcel A Level Maths 7.5 Proving Trigonometric Identities. Each one has a worked solution and a mark scheme showing where the marks go.

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