typora-copy-images-to: Khan Academy typora-copy-images-to: khan academy 文章目录 typora-copy-images-to: Khan Academy typora-copy-images-to: khan academy Khan Academy Precalculus Chapter 1 —— Trigonometry Introduction to the trigonometric angle addition identities Khan Academy Precalculus Chapter 1 —— Trigonometry range 对应的 domain must one on one 反三角函数的值域: 反三角函数的值域对应多个值,比如:sin(0)=sin(π)=0 ,因此我们为了定义反三角函数,必须限制原函数的定义域