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Maximum area of a rectangle inscribed in a semicircle of radius R (base on diameter):

AR²
BπR²
CR²/2
D2 R² / sqrt(2) = R² sqrt(2)
Answer & Solution
Correct answer: D. 2 R² / sqrt(2) = R² sqrt(2)
Width = 2x, height = sqrt(R² - x²). Area A = 2x sqrt(R² - x²). dA/dx = 0 gives x = R/sqrt(2). We have A_max = 2(R/sqrt(2)) sqrt(R² - R²/2). That is A_max = sqrt(2) R × (R/sqrt(2)) × sqrt(2). So A_max = R² sqrt(2). Wait, recompute: A = 2 × (R/√2) × √(R²/2) = 2 × (R/√2) × (R/√2) = R². So max area = R². (Width = R√2, height = R/√2.)
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