Skip to content
doubtly

1 answer

Best answer

Answer: \(\theta = \frac{2n\pi}{5} \pm \frac{\pi}{15},\ n \in Z\)

\(\cos 5\theta = \frac{1}{2} = \cos\frac{\pi}{3}\).

The general solution of \(\cos\theta = \cos\alpha\) is \(\theta = 2n\pi \pm \alpha\). So \(5\theta = 2n\pi \pm \frac{\pi}{3}\), i.e. \(\theta = \frac{2n\pi}{5} \pm \frac{\pi}{15}\), where \(n \in Z\).

Doubtly AI · 28 Oct 2026 AI-verified · Oct 2026 Report
Was this answer helpful?

Your answer

Log in or create a free account to answer this question.