In this situation, choose length and width such that 12.75=l*w. writing it as a mixed number you have 51/4=sqrt51/2*sqrt51/2 or any other combination you can use.
The circle with center (h, k) and radius r has equation
.. (x -h)^2 +(y -k)^2 = r^2
You have
.. h = 2
.. k = 0
.. r = √5
The center is (h, k) = (2, 0).
The area of the panel is 80ft^2
Let angle = x
sinx = 43.2/72.5
=> x = 36.57 degrees