The Function Graphed Is of the Form Y $$y = a \sin b x \text { or } y = a \cos b x , \text { where } b > 0$$

Multiple Choice

The function graphed is of the form y $$y = a \sin b x \text { or } y = a \cos b x , \text { where } b > 0$$ Determine the equation of the graph.
-The voltage $\mathrm { E }$ in an electrical circuit is given by $\mathrm { E } = 5.6 \cos 40 \pi \mathrm { t }$ , where $t$ is time measured in seconds. Find the frequency of the function (that is, find the number of cycles or periods completed in one second) .

A) $\frac { 1 } { 40 }$
B) $\frac { 1 } { 20 }$
C) 40
D) 20