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为什么sint/(1-cost)=cot(t/2)
人气:459 ℃ 时间:2020-06-15 14:47:30
解答
sint = 2sin(t/2)cos(t/2)
1-cost = 1-(1-2sin²(t/2))=2sin²(t/2)
所以
sint/(1-cost)=2sin(t/2)cos(t/2)/2sin²(t/2)=cos(t/2)/sin(t/2)=cot(t/2)
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