Question

вычислить
 sin780°  , cos 13П/6

Answer 1

$sin780^0=sin(720^0+60^0)=sin(4 pi +60^0)=sin60^0= frac{ sqrt{3} }{2}$

$cos frac{13 pi }{6} =cos( frac{12 pi }{6}+ frac{ pi }{6})=cos(2 pi + frac{ pi }{6})=cos frac{ pi }{6}= frac{ sqrt{3} }{2}$