Question

ПОМОГИТЕ РЕШИТЬ!!!!!!!

Answer 1

task/25238469
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4(Cos²π/8 -Sin²π/8) - 6Sin(π/4) =4*Cos(2*π/8) -6Sin(π/4) =
4*Cos(π/4) -6Cos(π/4) = -2Cos(π/4) = -2*(√2)/2 = - √2 . 

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Cos²φ -Sin²φ = Cos2φ  ; Sin(π/4) =Cos(π/4) = (√2)/2 .   π/4 =45°.