Question

只知道圆的面积,其他的都不知道,（圆周率取3.14）怎么算直径

Answer 1

S = πr²

r² = S/π

r = √(S/π)

d = 2r = 2√(S/π)

大圆直径 d = 2√(S/π) = 2√(720/π) = 24√(5/π)

小圆直径 d' = d/6 = 4√(5/π)

小圆半径 r' = d'/2 = 2√(5/π)

小圆面积S' = πr'² = π × 20/π = 20

10个小圆的面积和 = 10S' = 10 × 20 = 200 (cm²)