1) sin(-α)=-sinα, (1+sinα)(1-sinα)=1-sin²α=cos²α
2)tg(-α)=-tgα, -tgα*ctgα+sin²α=-(1-sin²α)=-cos²α
3)cos(-α)=cosα, cosα+cosα*tg²α=cosα(1+tg²α)=cosα*(1/cos²α)=1/cosα=secα
4) (1-sinα)/cosα+sinα/cosα=(1-sinα+sinα)/cosα=1/cosα=secα
5)(cos²α-cos^4α)/sin²α=cos²α(1-cos²α)/sin²α=cos²α*sin²α/sin²α=cos²α