Show that, for small values of θ\thetaθ measured in radians,
3cos2θ+sin4θ−2tan3θ≈A+Bθ+Cθ23 \cos 2\theta + \sin 4\theta - 2 \tan 3\theta \approx A + B\theta + C\theta^23cos2θ+sin4θ−2tan3θ≈A+Bθ+Cθ2
where AAA, BBB and CCC are constants to be found.
Use your answer to part (a) to find an approximation for
3cos0.12+sin0.24−2tan0.183 \cos 0.12 + \sin 0.24 - 2 \tan 0.183cos0.12+sin0.24−2tan0.18
Give your answer to three decimal places.
Practise Edexcel A Level Maths 5.5 Small Angle Approximations with exam-style questions for A Level Maths. 25 questions, 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.