Question

найти значение выражения

Answer 1

$= sqrt{27}-2 sqrt{27} cos^2 frac{11 pi }{12} =- sqrt{27}(2cos^2 frac{11 pi }{12} -1)=- sqrt{27}cos(2* frac{11 pi }{12})= \ =- sqrt{27}cos frac{11 pi }{6}=- sqrt{27}cos(2 pi - frac{ pi }{6})= \ = - sqrt{27}*cos frac{ pi }{6}=- sqrt{27}* frac{ sqrt{3} }{2}=- frac{ sqrt{81} }{2} =-4.5$