Additional Mathematics – Calculus | e-Consult

Using the quotient rule:

\(\displaystyle f'(x)=\frac{x\cos x-\sin x}{x^{2}}\)

Evaluating at \(x=\pi\):

\(\displaystyle f'(\pi)=\frac{\pi\cos\pi-\sin\pi}{\pi^{2}}=\frac{\pi(-1)-0}{\pi^{2}}=-\frac{1}{\pi}\)