三角関数の公式

$3$\displaystyle{{\sin }^{2}{\theta}+{\cos }^{2}{\theta}=1}$ ⇒証明

$3$\displaystyle{\tan {\theta}=\frac{\hspace{2} \sin {\theta} \hspace{2}}{\hspace{2} \cos {\theta} \hspace{2}}}$ ⇒証明

$3$\displaystyle{{\tan }^{2}{\theta}+1=\frac{\hspace{2}1\hspace{2}}{\hspace{2} { \cos }^{2}{\theta} \hspace{2}}}$ ⇒証明