(1) f(x)=-2sinxcosx+cos^2x+sin^2x+2sinxcosx+sinx×cosx/cosx=sinx+1 T=2π/1=2π(2) g(x)=3sin^2x+4sinx-1=3(sinx+2/3)^2-4/3-1=3(sinx+2/3)^2-7/3 最大值为 3(1+2/3)^2-7/3=6 最小值为3(-1+2/3)^2-7/3=2(3) g(x)-4f(x)=3sin^2x-1 为偶函数