Выражение (cos2t/cost+sint) -cost; tg(-t)*cost-sin(4п-t)

cos2t/(cost+sint) -cost=(cos²t-sin²t)/(cost+sint) -cost=
=(cost-sint)(cost+sint)/(cost+sint) -cost=cost-sint-cost=-sint

tg(-t)*cost-sin(4π-t)=-sint/cost *cost -(-sint)=-sint+sint=0