arccos(1) = 0, arccos(-1/2) = 2π/3, arccos(√3/2) = π/6

Таким образом, выражение равно 0 - 2π/3 + π/6 = -π/2

sin(π/6) = 1/2, arccos(1/2) = π/3

Ответ: π/3

arccos(-√2/2) = 3π/4, tg(3π/4) = -1

Ответ: -1