求下面各图中阴影部分的面积？ 求下面各图中阴影部分的面积
\u6c42\u4e0b\u9762\u5404\u56fe\u4e2d\u9634\u5f71\u90e8\u5206\u7684\u9762\u79ef\u3002\u7a7a\u767d\u7684\u9762\u79ef\u76f8\u5f53\u4e8e4\u4e2a\u76f4\u5f84\u4e3aa\u7684\u534a\u5706\u7684\u9762\u79ef-4\u4e2a\u76f4\u5f84\u4e3aa\u7684\u534a\u5706\u7684\u9762\u79ef-\u8fb9\u957f\u4e3aa\u7684\u6b63\u65b9\u4f53\u7684\u9762\u79ef
\u6240\u4ee5\u9634\u5f71\u90e8\u5206=\u8fb9\u957f\u4e3aa\u7684\u6b63\u65b9\u4f53\u7684\u9762\u79ef-\uff084\u4e2a\u76f4\u5f84\u4e3aa\u7684\u534a\u5706\u7684\u9762\u79ef-\u8fb9\u957f\u4e3aa\u7684\u6b63\u65b9\u4f53\u7684\u9762\u79ef\uff09
=2\u500d\u8fb9\u957f\u4e3aa\u7684\u6b63\u65b9\u4f53\u7684\u9762\u79ef-4\u4e2a\u76f4\u5f84\u4e3aa\u7684\u534a\u5706\u7684\u9762\u79ef
=2a^2-4*\u03c0\uff08a/2\uff09^2=(2-\u03c0\uff09a^2
\u6c42\u4e0b\u9762\u5404\u56fe\u5f62\u4e2d\u9634\u5f71\u90e8\u5206\u7684\u9762\u79ef\uff0e
\uff081\uff0910\u00d76\u00f72=30\uff08\u5e73\u65b9\u5398\u7c73\uff09\uff0c\u7b54\uff1a\u9634\u5f71\u90e8\u5206\u7684\u9762\u79ef\u662f30\u5e73\u65b9\u5398\u7c73\uff0e\uff082\uff0910\u00f72=5\uff08\u5398\u7c73\uff09\uff0c5\u00d75\u00f72=12.5\uff08\u5e73\u65b9\u5398\u7c73\uff09\uff0c\u7b54\uff1a\u9634\u5f71\u90e8\u5206\u7684\u9762\u79ef\u662f12.5\u5e73\u65b9\u5398\u7c73\uff0e
所以阴影部分=边长为a的正方体的面积-（4个直径为a的半圆的面积-边长为a的正方体的面积）
=2倍边长为a的正方体的面积-4个直径为a的半圆的面积
=2a^2-4*π（a/2）^2=(2-π）a^2
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