√2cos²x=cosx
√2cos²x-cosx=0
√2*cosx(cosx-√2/2)=0
cosx=0
x=π/2+π*n
cosx-√2/2=0
cosx=√2/2
x=+-π/4+2π*n
Б) [-7*π/2; -2π]
x=-7π/2
x=-3π
x=-2π
x=-π/4-2π=-9π/4
<span>1)=2sin2acosa\-2sin2asina=-cosa/sina=-tga
</span>
100мм = 1 дм
Ответ : 7200/100 = 72
(x-3)(x+3)/(x-3)(x-3)=(x+3)/(x-3), если х=-21, то (-21+3)/(-21-3)=-18/-24=0,75