Question 7 • Precalculus
The third side is 24 − 9 − 10 = 5 feet. The semiperimeter is 24 ÷ 2 = 12 feet, so Heron’s formula gives an area of √[12(12 − 9)(12 − 10)(12 − 5)] = √504 ≈ 22.45 square feet. Rounded to the nearest square foot, the area is 22 square feet, choice D.
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