Question

f'(n)=Cos(n-\frac{(2n+1)\pi}{6})

Answer 1

f(n) = \frac{3}{3-\pi} \sin\left(\frac{3-\pi}{3}n - \frac{\pi}{6}\right) + C

Answer 2

Integrate the given derivative f'(n) with respect to n after simplifying the argument of the cosine function.