[π(12√2)**2]/4 - π*6**2= 36π。用大圆半径12*√2，小圆半径6，因为阴影面积与半径无关。

来源: 湖西于 2025-07-03 19:38:55 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

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[π*(12*√2)**2]/4 - π*6**2= 36π。用大圆半径12*√2，小圆半径6，因为阴影面积与半径无关。