#ed_op#DIV#ed_cl# #ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#我錯了,難怪我不會證明.#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#我是看下面文章的第二項證明才說對角線垂直的:#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#A href="http://140.122.147.172/cultivation/93%E5%B9%B4/%E6%9C%9F%E6%9C%AB%E5%A0%B1%E5%91%8A/%E6%95%B8pdf/%E6%9E%97%E6%99%8F%E4%BD%91.pdf"#ed_cl#http://140.122.147.172/cultivation/93%E5%B9%B4/%E6%9C%9F%E6%9C%AB%E5%A0%B1%E5%91%8A/%E6%95%B8pdf/%E6%9E%97%E6%99%8F%E4%BD%91.pdf#ed_op#/A#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl# #ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#不過好像意思不大對.#ed_op#/DIV#ed_cl#亞斯 寫到:圓外切四邊形對角線不一定互相垂直#ed_op#BR#ed_cl#一個四邊形同時擁有外接圓與內切圓#ed_op#BR#ed_cl#它的對角線也不一定互相垂直#ed_op#BR#ed_cl#但是它對邊與內切圓切點連線會互相垂直