Take into account, that in general, a cosine function of amplitude A, period T and vertical translation b, can be written as follow:

In the given case, you have:
A = 4
T = 3π/4
b = -3
By replacing you obtain:

Hence, the answer is:
f(x) = 4cos(8/3 x) - 3
Answer:
0.6825
Explanation:
I'm not fully sure about how to do this, but I believe it might have to do with
the approx. amount of shade, but please take this explanation with a grain of salt as I'm not 100% certain. I am certain about the answer however.
Answer:
1. $0.99
2. $1.98
Step-by-step explanation:
1. From the question we have
Cost of box = $2.48
Selling price = $1.49
That is the box is discounted from $2.48 to $1.49
Therefore, amount saved = $2.48 - $1.49 = $0.99
2. The amount saved from buying a second box is hence;
2 × $0.99 = $1.98
Hence, as the number of boxes bought increases, the amount saved increases
The polygon is built of 7 triangles (picture).