=sin^2α/(sin α–cos α)+(sin α+cos α)/(1–(sin^2 α/cos^2α))=
=sin^2α/(sin α–cos α)+(sin α+cos α)/((cos^2α-sin^2α)/cos^2α)=
=sin^2α/(sin α–cos α)+(sin α+cos α)*cos^2α/((cosα-sinα)(cosα+sinα)=
=sin^2α/(sin α–cos α)+(cos^2α/(cosα-sinα))=
=(cos^2α/(cosα-sinα))-(sin^2α/(cosα-sinα))=
=(cos^2 альфа -sin^2 альфа )/(cos альфа -sin альфа )=
=cos альфа+sin альфа