We break down the area into two triangles - since we're given all their side lengths, we use Heron's formula: [tex][area]=\sqrt{s(s-a)(s-b)(s-c)},[/tex] where [tex]s=\frac{a+b+c}{2}[/tex]
[tex][ABD]=\sqrt{(265)(115)(85)(65)}\approx 12975.92[/tex]
[tex][CBD]=\sqrt{(225)(125)(75)(25)}\approx 7261.84[/tex]
[tex][ABCD]=[ABD]+[CBD]\approx\boxed{20238\,\text{m}^2}.[/tex]
