先化简f(x),得
f(x)
=a*(1+cos2x)+b*(1/2)*sin2x
=a+a*cos2x+(b/2)*sin2x
∵f(0)=2
∴a+a=2,得a=1
∵f(π/3)=1/2+√3/2
∴a-(a/2)+b*√3/4=1/2+b*√3/4
=1/2+√3/2
∴b=2
∴f(x)
=1+cos2x+sin2x
=1+√2*sin(2x+π/4)
(1)最小正周期是
T=2π/2=π
(2)容易知道
f(x)的最大值是
1+√2
此时
2x+π/4=π/2+2kπ,k∈Z
∴x的取值集合是
{x|x=π/8+kπ,k∈Z}
(3)f(x)的单调递减区间是
π/2+2kπ