вправа 11.16 гдз 10 клас математика Істер 2018

Умова:

Відповідь - ГДЗ:

1) cos(-585°) - sin225° - tg765° = cos(720° - 135°) -
- sin(180° + 45°) - tg(720° + 45°) =
= cos135° + sin45° - tg45° = - √2/2 + √2/2 - 1 = -1;
2) cos(-8π/3) - 1/2 sin(4π - π/6) - tg 13π/4 =
= cos(-2π - 2π/3) - 1/2sin(4π - π/6) - tg(2π + 5π/4) =
= cos 2π/3 + 1/2 sin π/6 - tg(π + π/4) =
= cos(π - π/3) + 1/4 tg π/4 = -cos π/3 + 1/4 - 1 =
= -1/2 + 1/4 - 1 = -5/4 = -1,25.