wangdan80
幼苗
共回答了14个问题采纳率:92.9% 举报
(1)
f(x)=2√3sinxcosx+2cos²x-1=√3sin2x+cos2x=2(√3/2sin2x+1/2cos2x)=2sin(2x+π/6)
函数的最小正周期T=π
(2)
f(x)=2sin(2x+π/6)=6/5
sin(2x+π/6)=3/5
x∈[π/4,π/2],
cos(2x+π/6)=-4/5
cos2x=cos(2x+π/6-π/6)=cos(2x+π/6)cosπ/6+sin(2x+π/6)sinπ/6=-4/5*√3/2+3/5*1/2=3/10-2√3/5
1年前
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