Question

Помогите решить пожалуйста!!!!
6) 2
11) 9, 10, 11, 12

Answer 1

1) sin210° = sin (180° + 30°) = - sin°30° = - 1/2;   2) cos135° = cos(180° - 45°) = - cos45° = - √2/2;   3) sin135° = sin(180° - 45°) = - sin45° = - √2/2;   4) ctg 225° = ctg (180° + 45°) = ctg 45° = 1;   5) cos 150° = cos (180° + 30°) = -  cos 30° =           - √3/2;   6) sin315° = sin(360° - 45°) = - sin 45° = - √2/2 ;   7)  ctg 240° = ctg (180° + 60°) = ctg 60° = √3/3;   8) tg 5π/4 = tg (π + π/4) = tg π/4 = 1;  9) sin 7π/6 = sin (π + π/6) = -  sin π/6 = - 1/2;  10) cos 5π/3 = cos (2π - π/3) = cos π/3     = 1/2; 11)  ctg 5π/3 = ctg (2π - π/3) = - √3/3;  12) sin ( - 13 π/6) = - sin ( π + π/6) = sin π/6 = 1/2;  13) tg ( - 2π/3) = - tg (2π/3) = - tg (π - π/3) = tg π/3 = √3; 14)  ctg ( - 7π/4) = - ctg (7π/4) = - ctg (2π - π/4) = ctg π/4 = 1                                                                2.  1) sinα = √1 - cos²α =√1 - 9/25 = 4/5;  tgα = sinα : cosα = (  4/5) : ( - 3/5) = - 4/3;  ctgα = - 3/4;   2) cosα = - √1 - sin²α = √1 - 4/25 = - √21/5;  tgα = sinα : cosα = ( - 2/5) : (  - √21/5) = 2/√21 = 2√21/21;  ctgα = √21/2