求函数y=[sin2x+sin(2x+π/3)]/[cos2x +cos(2x+π/3)]的最小正周期

问题描述:

求函数y=[sin2x+sin(2x+π/3)]/[cos2x +cos(2x+π/3)]的最小正周期
1个回答 分类:综合 2014-10-22

问题解答:

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y=[sin2x+sin(2x+π/3)]/[cos2x +cos(2x+π/3)]
=[sin2x+sin2xcosπ/3+cos2xsinπ/3]/[cos2x +cos2xcosπ/3-sin2xsinπ/3]
=[sin2x+1/2*sin2x+√3/2*cos2x]/[cos2x +1/2*cos2x-√3/2*sin2x]
=[3/2*sin2x+√3/2*cos2x]/[3/2*cos2x-√3/2*sin2x]
=√3(√3/2*sin2x+1/2*cos2x)/[√3(√3/2*cos2x-1/2*cos2x)]
=√3(sin2xcosπ/6+cos2xsinπ/6)/[√3(cos2xcosπ/6-sin2xsinπ/6)]
=(sin2xcosπ/6+cos2xsinπ/6)/(cos2xcosπ/6-sin2xsinπ/6)
=sin(2x+π/6)/cos(2x+π/6)
=tan(2x+π/6)
最小正周期T=π/w=π/2
 
 
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