1. Вычислите: А) sin 7п:3 Б) cos (-5п:4) В) tg (-13п:6) Г) ctg 13,5п 2. Решите уравнения: А) sin t=1/2 Б) cos t =-корень

1.

А) sin(3π) = sin(2π + π) = sin(π) = 0;

Б) cos(-5π/4) = cos(-π - π/4) = - sin(π/4) = -√2/2;

B) tg(-13π/6) = tg(-2π -  π/6) =tg(-π/6) = - 1/√3;

Г) ctg(13,5π) = ctg(13π + π/2) = ctg(π/2) = 0.

2.

A) sin(t) = 1/2

  t = arcsin(1/2) +- 2 * π * n, где n - натуральное число;

 t =  π/6 +- 2 * π * n;

Б) cos(t) = - √3/2

 t = arccos(- √3/2) +- 2 * π * n

 t = 5π/6 +- 2 * π * n.

3) cos(t) / sin(t) * ( sin(-t)) + cos(2π - t) = - cos(t) + cos(t) = 0.