Answer
$$A \approx 3650{\text{f}}{{\text{t}}^2}$$
Work Step by Step
$$\eqalign{
& a = 76.3{\text{ft}},\,\,\,b = 109{\text{ft,}}\,\,\,c = 98.8{\text{ft}} \cr
& {\text{First}},{\text{ find the semiperimeter }}s \cr
& s = \frac{1}{2}\left( {a + b + c} \right) \cr
& s = \frac{1}{2}\left( {76.3 + 109 + 98.8} \right) \cr
& s = 142.05 \cr
& \cr
& {\text{Now use Heron's formula to find the area }}A \cr
& A = \sqrt {s\left( {s - a} \right)\left( {s - b} \right)\left( {s - c} \right)} \cr
& A = \sqrt {142.05\left( {142.05 - 76.3} \right)\left( {142.05 - 109} \right)\left( {142.05 - 98.8} \right)} \cr
& {\text{Use a calculator}} \cr
& A \approx 3650{\text{f}}{{\text{t}}^2} \cr} $$
