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(tan(π/4+α)·cos2α)/2cos(π/4-α)
= (tan(π/4+α)·cos2α)/2sin(π/2-(π/4-α))
= (tan(π/4+α)·cos2α)/2sin(π/4+α)
=cos2α/(2sin(π/4+α))
=sin(π/2-2α)/(2sin(π/4+α))
= 2sin(π/4+α) cos(π/4+α) / (2sin(π/4+α))
= cos(π/4+α)
= (tan(π/4+α)·cos2α)/2sin(π/2-(π/4-α))
= (tan(π/4+α)·cos2α)/2sin(π/4+α)
=cos2α/(2sin(π/4+α))
=sin(π/2-2α)/(2sin(π/4+α))
= 2sin(π/4+α) cos(π/4+α) / (2sin(π/4+α))
= cos(π/4+α)
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