$(30\%)$ Study the signal shown below. The signal is input into an RC circuit as $Vs(t),$ and the circuit acts as a low pass filter which is described on the filter diagram shown.

Filter

$($a$)$ Sketch the frequency composition graph on figure $1$ b for the unfiltered signal shown in figure $1$ a $.$

$($b$)$ Sketch the frequency composition graph on figure $2b$ for the filtered signal shown in figure $2$ a $.$

$($c$)$ Find a $R()$ and