弧度(Radian)

彩色定义

\newcommand{\degree}{\color{c1}}
\newcommand{\radian}{\color{c2}}
\newcommand{\anglecolor}{\color{c3}}
\newcommand{\degreemeasure}{\color{c4}}
\newcommand{\radius}{\color{c5}}
\newcommand{\radianmeasure}{\color{c5}}

\displaystyle{
\degree \anglecolor{x}^{\degree{ \circ }}
}
\degree Degrees see \anglecolor{angles} \degree from the \ viewer's perspective (0--360 scale)

\displaystyle{
\radian \theta = \anglecolor \radius \frac{\anglecolor s}{r}
}

\radian Radians measure \anglecolor the mover's path \ \radius in terms of the radius
## 更多阅读 - [角度、度与弧度的直观指南](https://betterexplained.com/articles/intuitive-guide-to-angles-degrees-and-radians/)

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