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已知tana=-1/3,计算1/(2sinacosa+cos2a)
人气:175 ℃ 时间:2020-07-01 00:35:20
解答
1/(2sinacosa+cosa^2a)
=(sin^2a+cos^2a)/(2sinacosa+cosa^2a)
=[(sin^2a+cos^2a)/cos^2a]/[(2sinacosa+cosa^2a)/cos^2a]
=(tan^2a+1)/(2tana+1)
=[(-1/3)^2+1]/[2*(-1/3)+1]
=10/3
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