Find the value of
(i) `cos(-60^(@)) " "` (ii)`tan(210^(@))" "` (iii)` sin (300^(@))" "` (iv)`cos(120^(@))`

Explanation

(i) `cos (-60^(@))=cos 60^(@)=(1)/(2)`
(ii) `tan 210^(@)=tan(180^(@)+30^(@))=tan 30^(@)=(1)/sqrt(3)`
(iii) `sin 300^(@)=sin(270^(@)+30^(@))=-cos 30^(@)=-sqrt(3)/(2)`
(iv) `cos 120^(@)=cos(180^(@)60^(@))=0cos60^(@)=-(1)/(2)`