来自段旭东的问题
设a为第四象限的角,若sin3asina=135,则tan2a=______.
设a为第四象限的角,若sin3asina=135,则tan2a=______.
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2020-05-11 00:21
设a为第四象限的角,若sin3asina=135,则tan2a=______.
设a为第四象限的角,若sin3asina=135,则tan2a=______.
∵a为第四象限的角∴sinα<0,cosα>0∵sin3asina=sin(2α+α)sinα=sin2αcosα+cos2αsinαsinα=2cos2α+cos2α=4cos2α-1=135∴cosα=31010,sinα=-1010tanα=-13tan2α=2tanα1−tan2α=-34故答案为:-34...