已知cos(π-2α)/sin(α-(π/4)) =-负二分之根号二 求sinα+cosα=
人气:468 ℃ 时间:2020-01-28 14:13:42
解答
cos(π-2α)/sin(α-(π/4)) = -√2/22cos2α =√2sin(α-(π/4))=√2(sinαcosα(π/4)-cosαsin(π/4))= sinα-cosα2((cosα)^2-(sinα)^2 = sinα-cosα2(cosα+sinα)(cosα-sinα)= sinα-cosαsinα+cosα = ...
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