已知函数fx=2cosx·sin(x+π/3)-根号3sin2x+sinx·cosx当x∈0,π/2求fx值域

如题所述

第1个回答  2014-09-07
f(x)=2cosx*sin(x+π/3)-√3sin^2x+sinx*cosx
= 2cosx*sin(x+π/3)- 2sinx*[(√3/2)sinx-(1/2)cosx]
= 2cosx*sin(x+π/3)- 2sinx*[sin(π/3)sinx-cos(π/3)cosx)]
= 2cosx*sin(x+π/3)+ 2sinxcos(x+π/3)
= 2sin(2x+π/3)
又因为
当x∈0,π/2
所以F(x)∈【-√3,2】

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