高校问答汉口到光谷的地铁站名:证明sin3a=3sina-4sin立方a
来源：百度文库 编辑：高校问答 时间：2024/04/28 22:10:56
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sin3a=sin2a*cosa+cos2a*sina
=2sina*(cosa)^2+sina*(1-2(sina)^2)
=2sina-2(sina)^3+sina-2(sina)^3
=3sina-4(sina)^3
sin3a
=sin(2a+a)
=sin2a*cosa+cos2a*sina
=2sina*(cosa)^2+sina*[1-2(sina)^2]
=2sina-2(sina)^3+sina-2(sina)^3
=3sina-4(sina)^3
证明sin3a=3sina-4sin立方a
证明sin3a=3sina-4sin立方a
证明sin3a=3sina-4sin立方a
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