cos4x-sin2x=0 cos^22x-sin^22x-sin2x=0 1-2sin^22x-sin2x=0 2sin^22x+sin2x-1=0 sin2x=(-1+-3)/4 первый sin2x=-1 => 2x=-π/2+2πn => x=-π/4+πn второй sin2x=½ => 2x=(-1)^n•π/6+πn => x=(-1)^n•π/12+(π/2)•n
корни - x₁=3π/4, x₂=5π/12
