$\operatorname{ctg}52\degree22'33''?$  

 $\sin36\degree20'-\cos39\degree10'$  

Izračunaj: $\sin18\degree35'10''-2\cdot\cos18\degree35'10''$ 

Odredite   $\alpha$  ako je  $\operatorname{ctg}\ \alpha=2$  .