From the graph we notice that the period of the function is 2pi, this comes from the fact that the first maximum is at pi/4 and the second at 9pi/4, then the period is:
And hence the period of the function is 2pi.
Also, from the graph we notice that the amplitude is 7 this can be seen as follows: the amplitude is half the distance from the minimum to the maximum, then we have:
The vertical shift of the graph is -4 and the horizontal shift is pi/4 to the right; hence we have that the function is: