sin 960° = sin (720° + 240°) = sin 240° = sin (180° + 60°) = - sin 60° = - √ 3 / 2
cos 210° = cos (180° + 30°) = - cos 30° = - √ 3 / 2
ctg 660° = ctg (720° - 60°) - -ctg 60° = - √ 3 / 3
Тогда
4 * sin 960°- 8 * cos²210° + √ 27 * ctg 660°= 4 * (-√ 3 / 2) - 8 * (-√ 3 / 2)² + √ 27 *
(- √ 3 / 3) = -2 * √ 3 - 6 - 3 = - 2 * √ 3 - 9
огда