Graph:
Midline: the midline of a sinusoidal function is the horizontal center line about which the function oscilates.
For f(x)=cos(x) the midline is: y=0
Amplitude: half of the distance between maximum and minimum values of the function.
For f(x)=cos(x) the amplitude is: 1
Period: The sinisoidals functions repeat after a given value, the smallest such value is the period.
For f(x)=cos(x) the period is: 2π