已知tan(α+π\4)=2,求cos2α+3sin^2α的值
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已知tan(α+π\4)=2,求cos2α+3sin^2α的值
已知tan(α+π\4)=2,求cos2α+3sin^2α的值
已知tan(α+π\4)=2,求cos2α+3sin^2α的值
tan(α+π\4)=(tanα+tanπ\4)/(1-tanαtanπ\4)=2 求得tanα=1/3
cos2α+3sin^2α=1-2sin^2α+3sin^2α=1+sin^2α=11/10