Question

If you're good at trig please help meeeee Show full working out ;)

Answer 1

We break down the area into two triangles - since we're given all their side lengths, we use Heron's formula: $[area]=\sqrt{s(s-a)(s-b)(s-c)},$ where $s=\frac{a+b+c}{2}$

$[ABD]=\sqrt{(265)(115)(85)(65)}\approx 12975.92$

$[CBD]=\sqrt{(225)(125)(75)(25)}\approx 7261.84$

$[ABCD]=[ABD]+[CBD]\approx\boxed{20238\,\text{m}^2}.$