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Cos (x / 4 - α) = 12 / 13, α ∈ (0, π / 4), find (Cos2 α) / [sin (π / 4 + α)] Cos (x / 4 - α) = 12 / 13, α ∈ (0, π / 4), find (Cos2 α) / [sin (π / 4 + α)]
sin(π/4 + α)
=cos[π/2-(π/4 + α)]
=cos(π/4-α)=12/13
sin²(π/4-α)+cos²(π/4-α)=1
0
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