Answer:
area = 120√2 ft² or 169.71 ft²
Step-by-step explanation:
x² = 9² - 3² = 81 - 9 = 72
x = √72 = √(36 x 2) = 6√2 ft or 8.49 ft
area = 1/2(5 + 8)(6√2) = 120√2 ft² or 169.71 ft²
