To determine how much fencing Jamila needs, we first need to find the length of the diagonal of the square lot.
Given that the lot is a square and each side of the square is 209 feet (since an acre is defined as 1 acre = 43,560 square feet, and in this case, it's implied that the square shape has each side measuring the square root of 43,560, which equates to approximately 209 feet per side), we can use the Pythagorean theorem to calculate the length of the diagonal.
The formula for the diagonal \(d\) of a square with side length \(s\) is:
\[ d = s \sqrt{2} \]
Substituting \(s = 209\) feet into the formula:
\[ d = 209 \sqrt{2} \]
Calculating \(\sqrt{2} \approx 1.414\):
\[ d \approx 209 \times 1.414 \approx 295.46 \]
Rounding to the nearest foot, Jamila will need approximately:
\[ \text{Fencing needed} \approx 295 \text{ feet} \]
Thus, Jamila needs about 295 feet of fencing.