Answer:
[tex]900\sqrt{3}\:\mathrm{cm^2}\text{ or }\approx 1,558.85\:\mathrm{cm^2}[/tex]
Step-by-step explanation:
Heron's formula can be used to find the area of any triangle and is given by:
[tex]A=\sqrt{s(s-a)(s-b)(s-c)}[/tex], where [tex]a[/tex], [tex]b[/tex], and [tex]c[/tex] are three sides of the triangle and [tex]s[/tex] is the semi-perimeter ([tex]s=\frac{a+b+c}{2}[/tex]).
By definition, all three sides and angles of an equilateral triangle are equal. Therefore, if the total perimeter is 180 cm, each side must have a length of [tex]180\div 3=60\text{ cm}[/tex].
The semi-perimeter is therefore:
[tex]s=\frac{60+60+60}{2}=90\text{ cm}[/tex]
Substitute values into Heron's formula to get:
[tex]A=\sqrt{90(90-60)(90-60)(90-60)},\\A=\sqrt{90\cdot 30\cdot30\cdot 30},\\A=\sqrt{2,430,000},\\A=\boxed{900\sqrt{3} \:\mathrm{cm^2}}\approx \boxed{1,558.85\:\mathrm{cm^2}}[/tex]
