Answer:
y = 5
Step-by-step explanation:
That "+5" elevates the graph of this cosine function 5 units above the x axis, and thus the "midline" you wanted is y = 5.
I've labled all in red, hope this helps.
753.6
3.14x4²x15
r^2x15
137,638+52,091 is 189729.