If the effective collision diameter is 2d2d2d, what would be the cross-sectional area of that "danger zone" circle? (Recall the area of a circle is πr2\pi r^2πr2).
ВсеПолитикаОбществоПроисшествияКонфликтыПреступность，详情可参考新收录的资料
。业内人士推荐新收录的资料作为进阶阅读
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人类从历史中学到的，就是什么都没有学到……。新收录的资料是该领域的重要参考
// Imaging this code is in an implementation file.