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已知函数f(x)=(√3cosx-sinx)sin2x/2cosx+1/2.(1)求f(π/3)的值;(2)求函数f(x)的最小正周期及单调
递减函数
人气:197 ℃ 时间:2020-05-27 06:02:16
解答
cosαsinβ=[sin(α+β)-sin(α-β)]/2 f(x)=(√3cosx-sinx)sin2x/2cosx+1/2=(√3cosx-sinx)sinx+1/2=2cos(x+π/4)sinx+1/2=sin(x+π/4+x)-sin(x+π/4-x)+1/2=sin(2x+π/4)-(√2-1)/2后面的你会的.我不会化简和单调区间f(x)=(√3cosx-sinx)sin2x/2cosx+1/2=(√3cosx-sinx)sinx+1/2=2cos(x+π/6sinx+1/2=sin(x+π/6x)-sin(x+π/6-x)+1/2=sin(2x+π/6)则(1)f(π/3)=sin(2π/3+π/6)=1/2(2)T=2π/2=π单调递减区间为: [kπ+π/6,kπ+7π/6],k∈Z
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