$\sin {150}^o=\sin {30}^o=\cos {60}^o$  

$\sin {150}^o=\sin \left({90}^o+{60}^o\right)=\cos {60}^o$ $\sin {150}^o=\sin \left({90}^o+{60}^o\right)=\cos {60}^o$  

 

$\cos {150}^o=\cos \left({180}^o-{30}^o\right)=-\cos {30}^o$  

$\cos {150}^o=\cos \left({90}^o+{60}^o\right)=-\sin {60}^o$  

 

$\mathrm{tg}{150}^o=\mathrm{tg}\left({180}^o-{30}^o\right)=-\mathrm{tg}{30}^o$  

$\mathrm{tg}{150}^o=\frac{1}{\mathrm{tg}\left({90}^o+{60}^o\right)}=-\frac{1}{\mathrm{tg}{60}^o}$