Answer:
A ≈ 21.22 m²
Step-by-step explanation:
The area (A) of a triangle using Heron's formula is
A = [tex]\sqrt{s(s-a)(s-b)(s-c)}[/tex]
where s is the semi perimeter and a, b, c the sides of the triangle.
Here the perimeter of the equilateral triangle is 21 m , then
a = b = c = 21 ÷ 3 = 7 m
s = 21 ÷ 2 = 10.5
Then
A = [tex]\sqrt{10.5(10.5-7)(10.5-7)(10.5-7)}[/tex]
= [tex]\sqrt{10.5(3.5)(3.5)(3.5)}[/tex]
= [tex]\sqrt{450.1875}[/tex]
≈ 21.22 m² ( to 2 dec. places )
