§ 19: 19.1

19.1 Знайдіть значення виразу:

1) tg780° = tg(360° • 2 + 60°) = tg60° = 3;

2) cos(–750°) = cos750° = cos(360° • 3 + 30°) = cos30° = 32;

3) ctg225° = ctg(180° + 45°) = ctg45° = 1;

4) sin23π4 = sin(6π – π4) = sin(–π4) = –sinπ4 = –22;

5) cos7π4 = cos(2π – π3) = cos(–π4) = 22;