3.5 Trigonometry (A-level only)

Given that $\theta\,$ is small, use the small angle approximation of $\cos \theta\,$ to show that

\cos(3\theta) + \cos^2(\theta) \approx 3 - 10\theta^2 + 0.25\theta^4

[3]

Hence find an approximation of $\cos(3\theta) + \cos^2(\theta)$ when $θ=6∘\theta = 6^\circ$

[2]

Calculate the percentage error in your approximation

[1]

3.5 Trigonometry (A-level only) Questions

Given that $\theta\,$ is small, use the small angle approximation of $\cos \theta\,$ to show that

\cos(3\theta) + \cos^2(\theta) \approx 3 - 10\theta^2 + 0.25\theta^4

[3]

Hence find an approximation of $\cos(3\theta) + \cos^2(\theta)$ when $θ=6∘\theta = 6^\circ$

[2]

Calculate the percentage error in your approximation

[1]