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f(a)=sin(pai-a)cos(2pai-a)/cos(-pai-a)tana,则f(-31
/3pai)的值为
人气:203 ℃ 时间:2020-06-19 19:28:34
解答
f(a)=sinacosa/-cosatana=sinacosa/sina=cosa=cos(-31/3pai)=cos(2/3pai-12pai)=cos2/3pai=-1/2
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