2026 g12 t1 1

V = πr²h. r² + (h/2)² = R² => r² = R² - h²/4. V(h) = π(R² - h²/4)h = πR²h - πh³/4. V'(h) = πR² - 3πh²/4 = 0 => h = 2R/√3. r = R√(2/3).