Question

cos3x+cosx/1-sinx=0
cрочно надо!!!!!!!!помогите!!!!!

Answer 1

1-sinx≠0⇒sinx≠1⇒x≠π/2+2πn
cos3x+cosx=0
2cos2xcosx=0
cos2x=π/2+πn⇒x=π/4+πn/2
cosx=0 не удов усл