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已知tanα=1/2,则((1/4)sin^2)
((1/4)sin^2A+(3/4)cos^2A)/(sin^2A-cos^2A)
人气:213 ℃ 时间:2020-06-02 01:03:59
解答
[(1/4)sin^2A+(3/4)cos^2A]/(sin^2A-cos^2A)分子分母同时除以cos^2A=[(1/4)sin^2A/cos^2A+(3/4)cos^2A/cos^2A]/(sin^2A/cos^2A-cos^2A/cos^2A)=[(1/4)tan^2A+3/4]/(tan^2A-1)=[(1/4)*(1/2)^2+3/4]/[(1/2)^2-1]=[1/4*...
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