数学题：如图，平行四边形ABCD面积是72平方厘米，E是AD靠近D点的三等分点。BD与CE相交于点F，则图中阴影部分面积是多少平方厘米？

数学题解答：这题用比例做的。

BF：FD=△BEC：△CED=3：1（三角形同底，所以BF秘FD之比等于面积之比）

阴影面积=72×1/2×1/3×3/4=9（由开心糊涂老师解答）

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