2) sin(2x)=cos(3x) sin(2x)=cos(2x+x) sin(2x)=sos(2x)*cos(x)-sin(2x)*sin(x) sin(2x)=(1-2sin^2(x))*cos(x)-2sin(x)*cos(x)*sin(x) sin(2x)=cos(x)-2sin^2(x)*cos(x)-2sin^2(x)*cos(x) sin(2x)=cos(x)-4sin^2(x)*cos(x) 2sin(x)*cos(x)=cos(x)-4sin^2(x)*cos(x) cos(x)*[2sin(x)+4sin^2(x)-1]=0 1.cos(x)=0 x=pi/2+pi*n 2. 4sin^2(x)+2sin(x)-1=0 sin(x)=t 4t^2+2t-1=0 D=b^2-4ac=4+17=21 t1,2=(-b±sqrt(D))/2a t1=(-2+sqrt(21)/8 t2=(-2-sqrt(21)/8 sin(x)=(-2+sqrt(21))/8 x=(-1)^n*arcsin(-2+sqrt(21))/8+pi*n sin(x)=(-2-sqrt(21))/8 x=(-1)^n*arcsin(-2-sqrt(21))/8+pi*n
