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hollekitty 幼苗
共回答了1个问题 举报
(1/sin^2 x) + (1/cos^2 x) - （1/tan^2 x）= (1/sin^2 x*cos^2 x)-(cos^2 x/sin^2 x)
=(1-cos^4x)/sin^2 x*cos^2 x
=(1+cos^2x)sin^2x/sin^2 x*cos^2 x
==(1+cos^2x)/cos^2 x
=sec^2x+1=1+tan^2x+1= 2 + (tan^2 x)
希望对你有所帮助！
=(1-cos^4x)/sin^2 x*cos^2 x
=(1+cos^2x)sin^2x/sin^2 x*cos^2 x
==(1+cos^2x)/cos^2 x
=sec^2x+1=1+tan^2x+1= 2 + (tan^2 x)
希望对你有所帮助！
1年前
0
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