Giải phương trình: a) cos2x - sinx - 1 = cos3x; b) (tan^2x + tanx)/(tan^2x + 1) = √2/2.sin(x + π/4)

A) cos2x - sinx - 1 = cos3x
B) (tan^2x + tanx) / (tan^2x + 1) = √2/2 sin(x+π/4)