Given that θ \theta\,θ is small, use the small angle approximation of cosθ \cos \theta\,cosθ to show that
2cos(3θ)+cos2(θ)≈3−10θ2+0.25θ4 2 \cos(3\theta) + \cos^2(\theta) \approx 3 - 10\theta^2 + 0.25\theta^4 2cos(3θ)+cos2(θ)≈3−10θ2+0.25θ4Hence find an approximation of 2cos(3θ)+cos2(θ)2 \cos(3\theta) + \cos^2(\theta)2cos(3θ)+cos2(θ) when θ=6∘\theta = 6^\circθ=6∘
Calculate the percentage error in your approximation
Practise Edexcel A Level Maths Radians with exam-style questions for A Level Maths. 52 questions covering 5.1 Radian Measure, 5.2 Arc Length, 5.3 Areas of Sectors and Segments, 5.4 Solving Trigonometric Equations, and 5.5 Small Angle Approximations, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.