已知函数f(x)=2sin²(π/4+x)-根号3cos2x,x∈[π/4,π/2]
问题描述:
已知函数f(x)=2sin²(π/4+x)-根号3cos2x,x∈[π/4,π/2]
(1) 求f(x)的最大值最小值 (2)若不等式|f(x)-m|〈2恒成立,求m取值范围 求高手解答不要百度的要自己做的
答
(1)
f(x)=2sin²(π/4+x)-根号3cos2x
=1-cos(π/2+2x)-√3cos2x
=sin2x-√3cos2x+1
=2sin(2x-π/3)+1
∵ x∈[π/4,π/2]
∴ 2x-π/3∈[π/6,2π/3]
∴ sin(2x-π/3)∈[1/2,1]
∴ 2x-π/3=π/6时,f(x)有最小值2
2x-π/3=π/2时,f(x)有最大值3
(2)
|f(x)-m|