task/30380832 Преобразуйте сумму 1+2cos2α в произведение
" решение" 1+2cos2α =2(1/2 + cos2α) =2(cos(π/3) + cos2α) =
2*2cos( (π/3 +2α)/2) *cos( (π/3 -2α)/2) = 4cos(π/6 +α)*cos(π/6 - α).
* * * cosα + cosβ = 2cos( (α+β)/2 ) *cos( (α-β)/2 ) * * *
