已知θ是第三象限角,且sin4θ+cos4θ=5/9,那么sin2θ等于( )最后哪里的sin2θ方=8/9 ,我不明白,为什么(2sinθcosθ)方=8/9 就有了这步,2和cosθ到哪去了?sinθ方+cosθ方=1平方sinθ4方+cosθ4方+2sinθ方cos
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/07 12:37:57
![已知θ是第三象限角,且sin4θ+cos4θ=5/9,那么sin2θ等于( )最后哪里的sin2θ方=8/9 ,我不明白,为什么(2sinθcosθ)方=8/9 就有了这步,2和cosθ到哪去了?sinθ方+cosθ方=1平方sinθ4方+cosθ4方+2sinθ方cos](/uploads/image/z/995064-24-4.jpg?t=%E5%B7%B2%E7%9F%A5%CE%B8%E6%98%AF%E7%AC%AC%E4%B8%89%E8%B1%A1%E9%99%90%E8%A7%92%2C%E4%B8%94sin4%CE%B8%2Bcos4%CE%B8%3D5%2F9%2C%E9%82%A3%E4%B9%88sin2%CE%B8%E7%AD%89%E4%BA%8E%EF%BC%88%E3%80%80%E3%80%80%EF%BC%89%E6%9C%80%E5%90%8E%E5%93%AA%E9%87%8C%E7%9A%84sin2%CE%B8%E6%96%B9%3D8%2F9+%2C%E6%88%91%E4%B8%8D%E6%98%8E%E7%99%BD%2C%E4%B8%BA%E4%BB%80%E4%B9%88%EF%BC%882sin%CE%B8cos%CE%B8%EF%BC%89%E6%96%B9%3D8%2F9+%E5%B0%B1%E6%9C%89%E4%BA%86%E8%BF%99%E6%AD%A5%2C2%E5%92%8Ccos%CE%B8%E5%88%B0%E5%93%AA%E5%8E%BB%E4%BA%86%3Fsin%CE%B8%E6%96%B9%2Bcos%CE%B8%E6%96%B9%3D1%E5%B9%B3%E6%96%B9sin%CE%B84%E6%96%B9%2Bcos%CE%B84%E6%96%B9%2B2sin%CE%B8%E6%96%B9cos)
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