1+sin^2α-cos^2α-sinα/2sinαcosα-cosα
=[(1-cos^2a)+sin^2a-sina]/cosa(2aina-1)
=(2sin^2a-sina)/cosa(2sina-1)
=sina(2sina-1)/cosa(2sina-1)
=sina/cosa
=tana
1+sin^2α-cos^2α-sinα/2sinαcosα-cosα
=[(1-cos^2a)+sin^2a-sina]/cosa(2aina-1)
=(2sin^2a-sina)/cosa(2sina-1)
=sina(2sina-1)/cosa(2sina-1)
=sina/cosa
=tana