Question

A paper air plane looking polygon with sides of 5 5 and 8 what is the area

Answer 1

If it has 3 sides then it's a triangle. 
Using the formula $A= \sqrt{s(s-a)(s-b)(s-c)}$ 
where $s= \frac{a+b+c}{2}$
and  a=5 b=5 c=8

∴$s= \frac{5+5+8}{2} =9$
  $area= \sqrt{9(9-5)(9-5)(9-8)}$
  $area= \sqrt{144} = 12units^{2}$