Solve each problem. See Example 11.

Heron's formula gives a method of finding the area of a triangle if the lengths of its sides are known. Suppose that $a, b,$ and $c$ are the lengths of the sides. Let $s$ denote onenalf of the perimeter of the triangle (called the semiperimeter); that is, $s=\frac{1}{2}(a+b+c) .$ Then the area of the triangle is

$$

\mathscr{A}=\sqrt{s(s-a)(s-b)(s-c)}

$$

Find the area of the Bermuda Triangle, to the nearest thousand square miles, if the "sides" of this triangle measure approximately $850 \mathrm{mi}, 925 \mathrm{mi}$, and $1300 \mathrm{mi}$.