Решить уравнения : а ) sin 2x + 2 cos x = 0 б) cos 4x + sin22x = 0

Sin2x+2cosx=0
 2sinxcosx+2cosx=0
 2cosx(sinx+1)=0,
cosx=0, x=π/2+πn,n∈z,
sinx+1=0 , sinx=-1, x=-π/2+2πn,n∈z
2) cos4x+sin^22x=0,
  cos^22x-sin^22x+sin^22x=0,
 cos^22x =0, 2x=π/2+πn,n∈z, x=π/4+πn/2,n∈z..