2cos^2x-1=sin3x помогите решить 2+3

Question

2cos^2x-1=sin3x

помогите решить 2+3

Answer 1

 cos2x=sin3x
 sin3x-sin(π/2-2x)=0
 2sin(5x/2-π/4)cos(x/2+π/4)=0
 sin(5x/2-π/4)=0⇒5x/2-π/4=πn⇒5x/2=π/4+πn⇒x=π/10+2πn/5
 cos(x/2+π/4)=0⇒x/2+π/4=π/2+πn⇒x/2=π/4+πn⇒x=π/2+2πn
 x=π/10;π/2