Question

Use a graphing utility to graph the function
E(t) = 110 cos(120πt −π/3).
What is the period of the function?

Answer 1

The period of the function is the smallest T > 0 such that
E(t+T) = E(t)

Follow the procedure I used in the last question I answered for you to find T.

Answer 2

The period of a*Cos(b*t+c) is 2*Pi/b
So 2*Pi/(120*Pi) = 1/60 is the period