设函数f(x)=2cos^2(pai/4-x)+sin(2x+pai/3)-1,x属于R
问题描述:
设函数f(x)=2cos^2(pai/4-x)+sin(2x+pai/3)-1,x属于R
(1)求函数f(x)的最小正周期
(2)当x属于[0,pai/2]时,求函数f(x)的值域
答
f(x)=2cos^2(π/4-x)+sin(2x+π/3)-1
=1+cos(π/2-2x)+1/2sin2x+√3/2cos2x-1
=sin2x+1/2sin2x+√3/2cos2x
=3/2sin2x+√3/2cos2x
=√3sin(2x+π/6)
t=2π/2=π
x在[0,π/2]
2x+π/6在[π/6,7π/6]
函数f(x)的值域[-√3/2,√3]