1) Вычислите cos(-7/3) ∙ √3
2) Вычислите cos 11π/6 ∙ √3

Согласно формулам привдения 1) 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 = - √ 34) ctg (-3,5*π) = ctg (-3,5*π + 4*π) = ctg π/2 = 0