(sin 5п/18+sin 11п/9)/(cos 5п/18+cos 11п/9)
(sin 5п/18+sin 11п/9)/(cos 5п/18+cos 11п/9)=
= (2sin27pi/36 * cos17pi/36)/(2cos27pi/36 * cos17pi/36) = tg3pi/4 = -1
Ответ: -1