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sin(x)+cos(x)=2/3 根号2倍(sin(2x-π/4)+1)/1+tan(x)=?
2sin(x)*cos(x)+2sin(x)^2)/(1+tan(x))
=2sin(x)*cos(x)
怎么来的。
人气:255 ℃ 时间:2020-01-28 19:04:54
解答
根号2倍(sin(2x-π/4)+1)/1+tan(x)
=(sin(2x)-cos(2x)+1)/(1+tan(x))
=(2sin(x)*cos(x)+2sin(x)^2)/(1+tan(x))
=2sin(x)*cos(x)
又∵sin(x)+cos(x)=2/3
∴2sin(x)*cos(x)=(2/3)^2-1=-5/9
∴根号2倍(sin(2x-π/4)+1)/1+tan(x)=-5/9
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