三角函数的倍角问题

青青子衿

已知$\cos17x=f(\cos x)
则$\sin17x=f(\sin x)$
\(\color{blue}{\cos17x=f(\cos x)\phantom{\star}/\sin17x=f(\sin x)}\)
\[\cancelto{\cos17x}{\cos17x}\]
\(\color{green}{\cos17x=f(\cos x)\phantom{\star}\sin17x=f(\sin x)}\)

其妙

回复 1# 青青子衿
，$\cos17x=f(\cos x) $，则$\sin17x=f(\sin x)$，反斜杠的输入问题