已知sin(π/4 -α)=5/13,则sin2α/cos(π/4 +α)=_______.

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已知sin(π/4-α)=5/13,则sin2α/cos(π/4+α)=_______.已知sin(π/4-α)=5/13,则sin2α/cos(π/4+α)=_______.已知sin(π/4-α)

已知sin(π/4 -α)=5/13,则sin2α/cos(π/4 +α)=_______.
已知sin(π/4 -α)=5/13,则sin2α/cos(π/4 +α)=_______.

已知sin(π/4 -α)=5/13,则sin2α/cos(π/4 +α)=_______.
原式=2sinαcosα/(√2/2cosα-√2/2sinα)
sin(π/4 -α)=5/13平方可得2sinαcosα=119/169
代入上式可得=(119/169)/(5/13)=119/65