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来源:学生作业帮助网 编辑:作业帮 时间:2024/11/15 04:49:23
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sinα=[2tan(α/2)] / [1+(tan α/2)^2] =4/5
cosα=[1-(tan α/2)^2] / [1+(tan α/2)^2] =3/5
sin(β-α)=±√{1 - [cos(β-α)]^2} =±7√2/10
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