44) sin²α +cos(π/3 + α)*cos(π/3 -α) =
sin²α +(1/2)*(cos2α+cos2π/3) =sin²α +(1/2)*(1 -2sin²α -1/2) =
sin²α +(1/2)*(1/2 -2sin²α) = sin²α +1/4- sin²α =1/4.
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* cosα*cosβ =(cos(α -β) + cos(α +β))/2 преоб. произвед.в сумму *
* cos2α =cos²α - sin²α =1 -2sin²α *
45) cos2α/(1+sin2α) =(cos²α - sin²α)/(cos²α + sin²α +2sinαcosα) =
=(cosα - sinα)(cosα + sinα)/(cosα + sinα)² =
(cosα - sinα)/(cosα + sinα) =(1 -tqα)/(1+tqα) .