Part a.
The amplitude is the height from the center to the peak. We can note there are 8 units between consecutive peaks
Therefore, the midline passes at y=1:
So the amplitude is 4:
Therefore, the answers for part a are:
Midline: y=1
Amplitude: 4 units
Part b.
On the other hand, the period is 2Pi divided by the distance between consecitive peaks, that is,
so we get

which gives

thererefore, the period is 1 unit