古钱币|六年级奥数题及答案

古钱币|六年级奥数题及答案
 某仿古钱币直径为4厘米，钱币内孔边缘恰好是圆心在钱币外缘均匀分布的等弧(如图).求钱币在桌面上能覆盖的面积为多少?

   答案：

    
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