3
[siny-cosy(siny/cosy+cosy/siny)]:cosy=
=[siny-cosy*(sin²y+cos²y)/sinycosy]:cosy=
=(siny-1/siny):cosy=(sin²y-1)/siny:cosy=
=-cos²y/(sinycosy)=-cosy/siny=-ctgy
4
(sin²β/cos²β -sin²β):(cos²β/sin²β-cos²β)=
=sin²β(1-cos²β/cos²β:cos²β(1-sin²β)/sin²β=
=sin^4β/cos²β*sin²β/cos^4β=sin^6β/cos^6β=tg^6β