sin^2/(sin-cos) - (sin+cos)/(tan^2 -1)
=sin^2/(sin-cos) -(sin+cos)/[(sin^2/cos^2)-1]
=sin^2/(sin-cos) -(sin+cos)cos^2/(sin^2-cos^2)
=sin^2/(sin-cos) -cos^2/(sin-cos)
(sin^2-cos^2)/(sin-cos)
=sin-cos