Answer :
Answer: 528.19 square cm (approximate)
Explanation
Use the circumference to find the radius.
C = 2pi*r
81.45 = 2*3.14*r
81.45 = 6.28*r
r = 81.45/6.28
r = 12.969745 approximately
Then we can determine the area.
A = pi*r^2
A = 3.14*(12.969745)^2
A = 528.1928560462
A = 528.19
I rounded to two decimal places since both the 81.45 and 3.14 are also to two decimal places. Round the final answer to however your teacher instructs.