Find the area of the triangle $A B C$.
\[
a=100.9 m \quad b=87.4 m \quad c=92.9 m
\]

Step 1 ：Given a triangle ABC with sides a = 100.9 m, b = 87.4 m, and c = 92.9 m.

Step 2 ：To find the area of the triangle, we can use Heron's formula. Heron's formula states that the area of a triangle is equal to the square root of the product of the semi-perimeter of the triangle and the difference of the semi-perimeter and each side.

Step 3 ：The semi-perimeter of a triangle is half the sum of the lengths of its sides. So, first we calculate the semi-perimeter (s) as follows: \(s = \frac{a + b + c}{2} = \frac{100.9 + 87.4 + 92.9}{2} = 140.6\) m.

Step 4 ：Then, we can use the semi-perimeter to calculate the area (A) using Heron's formula: \(A = \sqrt{s(s - a)(s - b)(s - c)} = \sqrt{140.6(140.6 - 100.9)(140.6 - 87.4)(140.6 - 92.9)} = 3763.60\) m².

Step 5 ：Final Answer: The area of the triangle ABC is \(\boxed{3763.60 \, m^2}\).