作业帮cos2x/根号2cos(x+π/4)=1/5,0
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cos2x/根号2cos(x+π/4)=1/5,0
cos2x/根号2cos(x+π/4)=1/5,0
cos2x/根号2cos(x+π/4)=1/5,0
(cos2x)/√2cos(x＋π/4)＝(cos²x－sin²x)/[√2(cosxcos(π/4)－sinxsin(π/4))]＝[(cosx＋sinx)(cosx－sinx)]/(cosx－sinx)＝cosx＋sinx＝1/5即可.
cos2x/√2cos(x+π/4)=1/5
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cos2x/根号2cos(x+π/4)=1/5,0
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