1. **State the problem:** We are given a cone with sides AB = 20.7 feet (radius), BC = 81.9 feet, and CA = 84.5 feet (slant height). We need to find the surface area of the cone using the formula $$SA = \frac{1}{2} P s + B$$ where $P$ is the perimeter of the base, $s$ is the slant height, and $B$ is the area of the base. 2. **Identify given values:** - Radius $r = AB = 20.7$ feet - Slant height $s = CA = 84.5$ feet 3. **Calculate the perimeter $P$ of the base:** The base is a circle, so the perimeter (circumference) is $$P = 2 \pi r = 2 \times 3.14 \times 20.7 = 129.996 \approx 130$$ feet 4. **Calculate the area $B$ of the base:** $$B = \pi r^2 = 3.14 \times (20.7)^2 = 3.14 \times 428.49 = 1344.64$$ square feet 5. **Calculate the surface area $SA$:** $$SA = \frac{1}{2} P s + B = \frac{1}{2} \times 130 \times 84.5 + 1344.64$$ $$= 65 \times 84.5 + 1344.64 = 5492.5 + 1344.64 = 6837.14$$ square feet **Final answer:** The surface area of the cone is approximately **6837.14 square feet**.