<span>sin П/12 - cos П/12)^2 = sin^2П/12 + cos^2П/12 - 2sinП/12*cosП/12 = 1 - sin 2*П/12 = 1 - sinП/6 = 1 - 1/2 = 1/2</span>
1.5x -36 -5x -120 =23
-3.5x -156 =23
-3.5x =23+156
-3.5x =179
-x =179 : 35/10
x =( -179*10)/35
х =(-179*2)/7
x =(-51 целая 1/7)
(lg10+lgx)^2+lgx=19
1+2lgx+lg²x+lgx-19=0
lg²x+3lgx-18=0
lgx=a
a²+3a-18=0
a=3, a=-6
lgx=3 ili lgx=-6
x=10³ x=10⁻⁶
x₁=1000 x₂=0,000001