Помогите пожалуйста с уравнениями
1)sin7x*cos5x-sin2x=0
2)3cos2x-1=ctg2x*sin4x
3)sin4x=cos5x-cosx
4)sin3x*cos4x+sinx*cos8x=0

11/2*sin2x+1/2*sin12x-sin2x=01/2*sin12x-1/2*sin2x=01/2*(sin12x-sin2x)=01/2*sin5xcos7x=0sin5x=0⇒5x=πn,n∈z⇒x=πn/5,n∈zcos7x=0⇒7x=π/2+πk,k∈z⇒x=π/14+πk/7,k∈z23cos2x-1=cos2x/sin2x*2sin2x*cos2x3cos2x-1=2cos²2xcos2x=a2a²-3a+1=0D=9-8=1a1=(3-1)/4=1/2⇒cos2x=1/2⇒2x=+-π/3+2πn⇒x=+-π/6+πn,n∈za2=(3+1)/4=1⇒cos2x=1⇒2x=2πk⇒x=πk,k∈z32sin2x*cos2x=-2sin2x*sin3x2sin2x*(cos2x+sin3x)=0sin2x=0⇒2x=πn⇒x=πn/2,n∈zcos2x+sin3x=0cos2x+cos(π/2-3x)=02cos(π/4-x/2)cos(5x/2-π/4)=02sin(x/2-π/4)cos(5x/2-π/4)=0sin(x/2-π/4)=0⇒x/2-π/4=πn⇒x/2=π/4+πn⇒x=π/2+2πn,n∈zcos(5x/2-π/4)=0⇒5x/2-π/4=π/2+πk⇒5x/2=3π/4+πk⇒x=3π/10+2πk/5,k∈z41/2*sin(-x)+1/2*sin7x+1/2*sin(-7x)+1/2*sin9x=01/2*sin9x-1/2*sinx=01/2*(sin9x-sinx)=01/2*2sin4xcos5x=0sin4x=0⇒4x=πn⇒x=πn/4,n∈zcos5x=0⇒5x=π/2+πk⇒x=π/10+πk/5,k∈z