cos (4x + Pi/2) =√ 2 cos2x; [-3Pi; -2pi]- sin 4x = √2 cos2x√2 cos2x + 2 sin2x cos2x = 0cos2x ( √2 + 2 sin2x) = 0[ cos2x = 0 ,[ sin2x = -√2/2,1) cos2x = 0, 2x=Pi/2+Pin, n€Z,x=Pi/4+Pin/2, n€Z,x=-9Pi/4, x=-11Pi/4, € [-3Pi; -2pi]....2)sin2x = -√2/2,2x=(-1)^(k +1) *Pi/4 +Pik, k€Z,x=(-1)^(k +1) *Pi/8 +Pik/2, k€Z,x1=-Pi/8 +Pik, k€Z,x2= 5Pi/8 +Pik, k€Z,Отбираем х€ [-3Pi; -2pi]-3Pi≤-Pi/8 +Pik≤-2pi, k€Z,-3+1/8≤k≤-2+1/8, k€Z,k=-2, x=-17Pi/8;....-3Pi≤5Pi/8 +Pik≤-2pi, k€Z-3-5/8 ≤k≤-2 -5/8; k€Zk=-3, x=-19Pi/8....Ответ: a)Pi/4+Pin/2, n€Z,;(-1)^(k +1) *Pi/8 +Pik/2, k€Z,b)-19Pi/8;-17Pi/8;-11Pi/4;-9Pi/4,