1. ≡ -26/sin(2π·4 -π/6) *cos(2π·5 +2π/3) =
= 26/sinπ/6 *cos2π/3 = 26/(1/2) * (-1/2) закончи сам, т.к. не могу угадать * под дроби или ...
2(. 12√[6sin(2π·4+π/4)·√3/2] = 12√(6·√2/2 ·√3/2) = 12·6/2 = 36
3). cos(-x) =cosx
9/[4cos(2π·2+π/6) ·sin(2π·19- π/3)] =
= 9/[4·cosπ/6·(-sinπ/3)] = 9/[4·√3/2 ·(-√3/2) = - 3