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sinα=3╱5求sin2(α-π/4)
人气:295 ℃ 时间:2020-02-05 10:52:17
解答
sin2(a-π/4)
=sin(2a-π/2)
=-cos2a
=-1+2(sina)^2
=-1+2(3/5)^2
=-1+18/25
=-7/25
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