1) 1- sin²α-cos²α=1-(sin²α+cos²α)=1-1=0
2) cos²α-(ctg²α+1)sin²α=cos²α-(cos²α/sin²α+1)sin²α=cos²α-(cos²α+sin²α)=cos²α-1
3)(1-sinαcosα)/(cos²α-sin²α)=(1-√3/4)/(1/4-3/4)=-2-√3
4)tgα/(1-tg²α)*(ctg²α-1)/ctgα=1
sinα*cos²α (cos²α-sin²α)sinα sin²α*cos²α
------------------------ * ------------------------ =----------------- = 1
cosα(cos²α-sin²α) sin²α cosα sin²α*cos²α