oblicz wartość wyrażenia: cos(10pi/3) * sin(7pi/4) + tg(2pi/3) * ctg(7pi/3) bardzo proszę o pomoc

oblicz wartość wyrażenia: cos(10pi/3) * sin(7pi/4) + tg(2pi/3) * ctg(7pi/3) = cos(2π+1 i 1/3π) * sin(2π-1/4π) + tg(π-1/3π) * ctg(2π+1/3π)= cos(π+1/3π) * [-sin(1/4π)] - tg(1/3π) * ctg(1/3π) = [-cos(1/3π)] * [-sin(1/4π)] - tg(1/3π) * ctg(1/3π) =(-1/2)*(-√2/2)-√3*√3/3= √2 /4-1