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证明:1-2(secα)^2=(tanα)^4-(secα)^4
人气:353 ℃ 时间:2020-08-27 23:05:30
解答
(tanα)^4-(secα)^4
=(tan^a-sec^2a)(tan^a+sec^2a)
=-(tan^a+sec^2a)
=-(sec^2a-1+sec^2a)
=1-2(secα)^2
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