f(x)=√2｜向量A＋向量B｜=√2√(sin3x/2+cosx/2)^2+(cos3x/2+sinx/2)^2=√2√[2+2(sin3x/2 cosx/2+cos3x/2 sinx/2)=√2√(2+2sin2x)=2√(1+sin2x）=2√(sin^2x+cos^2x+2cosxsinx=2|sinx+cosx|=2√2|sin(x+π/4)|最...