The Area of a Triangle with Side Lengths $a, b, c$

Short Answer

The area of a triangle with side lengths $a, b, c$ is given by $A=\sqrt{s(s-a)(s-b)(s-c)}$ , where $\mathrm{s}=(a+b+c) / 2$ . What is the area of an equilateral triangle with side length $1.3 \mathrm{~cm}$ ?