# What is the frequency of f(theta)= sin t - cos 4 t ?

$2 \pi$
Period of sin t --> $2 \pi$
Period of cos (4t) --> $\left(2 \frac{\pi}{4}\right) = \frac{\pi}{2}$
Period of f(t) -->$\left(2 \pi\right)$ --> least common multiple of $\left(2 \pi\right)$ and $\left(\frac{\pi}{2}\right)$.