求证:2sinα+sin2α=2sin^3α/(1-cosα)
来源:学生作业学帮网 编辑:学帮网 时间:2024/06/01 05:46:35
求证:2sinα+sin2α=2sin^3α/(1-cosα)
2sina+sin2a
=2sina+2sinacosa
=2sina(1+cosa)=2sin^3a(1+cosa)/sin^2a
=2sin^3a(1+cosa)/(1-cos^2a)
=2sin^3a/(1-cosa)
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来源:学生作业学帮网 编辑:学帮网 时间:2024/06/01 05:46:35
求证:2sinα+sin2α=2sin^3α/(1-cosα)
2sina+sin2a
=2sina+2sinacosa
=2sina(1+cosa)=2sin^3a(1+cosa)/sin^2a
=2sin^3a(1+cosa)/(1-cos^2a)
=2sin^3a/(1-cosa)