三角函数反映了圆运动和直线运动的相互转化与对应关系，是初等函数中唯一的周期函数。

Trigonometrical function reflects Yuan Movement and the Movement of mutual conversion and the corresponding linear relationship is the only primary function of the cycle function .

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三角函数反映了圆运动和直线运动的相互转化与对应关系，是初等函数中唯一的周期函数。

Trigonometrical function reflects Yuan Movement and the Movement of mutual conversion and the corresponding linear relationship is the only primary function of the cycle function .

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