Chrome，
QQ浏览器
-
-
-
-
![人教A高中数学必修五1.1.2 余弦定理[胡光启]【市一等奖】优质课](//imgshow.1ydt.com/img?url=%2F%2Fi2.hdslb.com%2Fbfs%2Farchive%2Fed3fac9029316ba6585b69fe1f6ff55b022f34a7.jpg%40672w_378h_1c_%21web-search-common-cover)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
![高中教材上没有的射影定理，大有用处！[高一春季5]](//imgshow.1ydt.com/img?url=%2F%2Fi0.hdslb.com%2Fbfs%2Farchive%2F7813c6d795c699d15165603c47be5eb164daacdb.jpg%40672w_378h_1c_%21web-search-common-cover)
-
-
-
-
-
-
-
-
-
播放：24 时间：2024-06-19简介： -
.
![人教A高中数学必修五1.1.2 余弦定理[胡光启]【市一等奖】优质课](http://imgshow.1ydt.com/img?url=%2F%2Fi2.hdslb.com%2Fbfs%2Farchive%2Fed3fac9029316ba6585b69fe1f6ff55b022f34a7.jpg%40672w_378h_1c_%21web-search-common-cover)
![高中教材上没有的射影定理，大有用处！[高一春季5]](http://imgshow.1ydt.com/img?url=%2F%2Fi0.hdslb.com%2Fbfs%2Farchive%2F7813c6d795c699d15165603c47be5eb164daacdb.jpg%40672w_378h_1c_%21web-search-common-cover)
.