Chrome，
QQ浏览器
.
![人教A高中数学必修四1.2.1 任意角的三角函数[马芬]【市一等奖】优质课](http://imgshow.1ydt.com/img?url=%2F%2Fi1.hdslb.com%2Fbfs%2Farchive%2Fc84924d3f019c1daee8d61cae4b3fd33e9134b4b.jpg%40672w_378h_1c_%21web-search-common-cover)
![[三角函数1]角的概念的推广——任意角](http://imgshow.1ydt.com/img?url=%2F%2Fi0.hdslb.com%2Fbfs%2Farchive%2F88bbf2229a4ce2c9b66392d13c665bf1032142f7.jpg%40672w_378h_1c_%21web-search-common-cover)
.