Given that θ \theta\,θ is small and measured in radians, show that
sin4θ−tan2θθ(1−cos3θ)\displaystyle \frac{\sin 4\theta - \tan 2\theta}{\theta\left(1 - \cos 3\theta\right)}θ(1−cos3θ)sin4θ−tan2θ
can be approximated by Aθ2\dfrac{A}{\theta^2}θ2A, where A A\,A is a constant to be found.
Use your answer to part (a) to estimate the value of the expression when θ=0.02\theta = 0.02θ=0.02.
Explain why the approximation becomes less reliable as θ \theta\,θ increases.