kratgv

Verified answer

1) = (1 + Cosα)(1 - Cosα)*Ctg²α = (1 - Cos²α) * Ctg²α = Sin²α * Cos²α/Sin²α=
=Cos²α
2) = 1 - Sinα* Cosα/Sinα * Cosα = 1 - Cos²α = Sin²α
3) = tgα*tgβ