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已知函数f (x )=4sinxcos (x +π/3)+√3.(1)求f (x )最小正周期 (2)求f (x )在区

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已知函数f (x )=4sinxcos (x +π/3)+√3.(1)求f (x )最小正周期 (2)求f (x )在区间 [-π/4,π/
已知函数f (x )=4sinxcos (x +π/3)+√3.(1)求f (x )最小正周期 (2)求f (x )在区间 [-π/4,π/6]上的最大值和最小值及取得最大值时x 的值.
解f (x )=4sinxcos (x +π/3)+√3
=2×2sinxcos (x +π/3)+√3
=2×[sin(x+x+π/3)+sin(x-x-π/3)]+√3
=2×[sin(2x+π/3)+sin(-π/3)]+√3
=2sin(2x+π/3)+2sin(-π/3)+√3
=2sin(2x+π/3)+2*(-√3/2)+√3
=2sin(2x+π/3)
故T=2π/2=π 再答: (2)由x属于[-π/4,π/6] 即-π/4≤x≤π/6 即-π/2≤2x≤π/3 即-π/6≤2x+π/3≤2π/3 即-1/2≤sin(2x+π/3)≤1 即-1≤2sin(2x+π/3)≤2 即f (x )在区间 [-π/4,π/6]上的最大值为2,最小值-1 当x=π/12时,y有最大值为=2 当x=-π/4时,y有最小值为=-1/2。