已知tana=2,求2/3sin^2a-sinacosa+cos^2a的值
人气：445 ℃ 时间：2020-04-25 13:44:56
解答
(2/3sin^2a-sinacosa+cos^2a)/cos^2a*cos^2a=(2/3tan^2a-tana+1)*cos^2a=5cos^2a/3tana=2sina/cosa=2sin^2a/cos^2a=4(1-cos^2a)/cos^2a=4cos^2a=1/5(2/3sin^2a-sinacosa+cos^2a)/cos^2a*cos^2a=(2/3tan^2a-tana+1)*c...
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