Chrome，
QQ浏览器
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![人教数学九上24.4探究圆的弧长、扇形面积公式[董老师]【市一等奖】优质课](//imgshow.1ydt.com/img?url=%2F%2Fi2.hdslb.com%2Fbfs%2Farchive%2F12de77bc7639fe3662a61e943a21c322dc7fb348.jpg%40672w_378h_1c_%21web-search-common-cover)
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播放：15 时间：2024-06-21简介： -
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![人教数学九上24.4探究圆的弧长、扇形面积公式[董老师]【市一等奖】优质课](http://imgshow.1ydt.com/img?url=%2F%2Fi2.hdslb.com%2Fbfs%2Farchive%2F12de77bc7639fe3662a61e943a21c322dc7fb348.jpg%40672w_378h_1c_%21web-search-common-cover)
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