<span>cosx+cos2x+cos3x<0</span>
<span>cos2x+2cos * x+3x/2 * cos* x-3x/2<0</span>
<span>cos2x+2cos2x*cosx<0</span>
<span>cos2x(1+2cosx)<0</span>
<span>cos2x(cos0+2cosx)<0</span>
<span>cos2x * 2cos x/2 * cos x/2 <0</span>
<span>2cosx * cos (квадрат) x/2 <0</span>
все)
2.3+2.3+4.1+4.1=12.8 м - комната
12.8/1.6 = 8 рулонов