4cosxsin2xsinx=1
4sinxcox+1=0
tgx≤1
√2sin3x=1
sin3x=sin5x
y=3-4sin²xcos2x

1) 4sinx*cosx*sin2x =1 ;2sin2x*sin2x =1 ;sin²2x =1/2 ;( 1 -cos4x) /2 =1/2 ; 1 -cos4x =1 ;cos4x =0 ⇒ 4x =π/2 +π*K⇒ x =π/8 +(π/4)*k ; k∈Z.-----------------------2) tg x≤ 1 ;  - π*k - π/2 ≤ x ≤  π/4  + π*k .3) √2sin3x=1 ;sin 3x =1/√2 ;3x =(-1)^k*π/4 +2π*k ;x =(-1)^k*π/12 +2π*k ; k ∈Z ..4)  sin3x=sin5x ;sin5x - sin3x =0 ;2sin(5x - 3x)/2 *cos(5x + 3x)/2 =0 ;2sinx *cos4x =0 ;[ sinx =0 ; cos4x =0⇒[x =π*k ; 4x= π/2+π*k .[x =π*k ; x= π/8+π/4*k ;k ∈Z .