The solution is in the attached below
Circumference=31.4yd

Answer:
P(x) = 0.50x - 5
Step-by-step explanation:
x = number of glasses sold
She charges $0.50 per glass, so her revenue is
R(x) = 0.50x
which is the amount of money she brings in
Her cost function is
C(x) = 5
assuming she only spends that $5.00 on the supplies mentioned.
The profit P(x) is the difference of revenue and cost
Profit = Revenue - Cost
P(x) = R(x) - C(x)
P(x) = 0.50x - 5
I think you can use cosine rule if only the lines that form the <52 are equal.
1.5x + 7 = 20.5
First subtract 7 from both sides
1.5x = 13.5
Then divide both sides by 1.5
x = 9
Let me know in comments if you have questions