Answer
a) period is $880\pi$
b) frequency is 0.00036
Work Step by Step
a) the period is found as the variable $k$ in the base function $f(t)=a\cdot cos(k(t-b))$ In this case one can see that it is $800\pi$
b) The frequency is the inverse of the period $p=\frac{1}{f}$, so the frequency in this example is $\frac{1}{880\pi}$ or $\approx0.00036$
