cos (-5) = - 0.5 sin (-x/4) = ^2/2 tg (-x/3)) = ^3 ctg (-6x) = - 1

Согласно формулам приведения1) cos 5*π/6 = - cos (π - 5*π/6) = - cos π/6 = - √ 3 / 22) sin (-7*π/4) = sin (-7*π/4 + 2*π) = sin π/4 = √ 2 / 23) tg 11*π/3 = tg (11*π/3 - 4*π) = tg (-π/3) = - tg π/3 = - √ 3 4) ctg (-3,5*π) = ctg (-3,5*π + 4*π) = ctg π/2 = 0