What is the equation for the graph of the cosine function?
We have the following form
f(x) = Acos (Bx + C) + D
A = the amplitude = [ high point - low point ] / 2 = [ 4.5 - 3.5 ] / 2 = 1/2
The period is pi
So
B = 2pi / period = 2pi / pi = 2
C = phase shift ....there is none
D = this is the cosine graph with an amplitude of 1/2 shifted up 4 units......so 4
So....the graph is
f(x) = (1/2) cos (2x) + 4
Thanks to EP for pointing out my error.....!!!