1-2cos(3П/2+2П/6)=,,,

1-2cos(3π/2+2π/6)=1-2cos(11π/6)=1-2*√3/2=1-√3

[latex]1-2cos( \frac{3 \pi }{2} + \frac{2 \pi }{6} )=1-2cos( \frac{9 \pi }{6} + \frac{ 2\pi }{6} )= 1-2cos \frac{11 \pi }{6} = \\ = 1-2cos \frac{11 \pi }{6} = 1-2cos( \pi + \frac{5 \pi }6} )=1-2cos( \pi + \pi - \frac{ \pi }{6} )= \\ =1-2cos(- \frac{ \pi }{6} )=1-2cos \frac{ \pi }{6} =1-2* \frac{ \sqrt{3} }{2} =1- \sqrt{3} [/latex]