1) а) cos π +ctg 4π/3 б)tg(-11π/6) 2) a)cos t=1/2 sin-? cos (π/2+t) sin-? подробнее !

1.а)cosπ+ctg4π/3=cosπ+ctgπ/3=-1+√3/3
б)tg(-11π/6)=tg(-2π+π/6)=tgπ/6=√3/3
2)cost=1/2 ⇒t=π/3+2kπ;k∈Z, ⇒sinπ/3=√3/2;
cos(π/2+t)=-sint