Standard +0.3 This is a straightforward small angle approximation question requiring standard substitutions (cos x ≈ 1 - x²/2, sin x ≈ x) and basic algebraic manipulation. While it involves the compound angle 3θ and 2θ, the technique is routine and commonly practiced, making it slightly easier than average for A-level.
When $\theta$ is small, find an approximation for $\cos 3\theta + \theta \sin 2\theta$, giving your answer in the form $a + b\theta^2$
[3 marks]
\hfill \mbox{\textit{AQA Paper 1 Q3 [3]}}