Question

1+cosa - (sin^2a cosa)/1-cosa

Answer 1

$1+cos \alpha -\frac{sin^2 \alpha \cdot cos \alpha }{1-cos \alpha }=\frac{(1+cos \alpha )(1-cos \alpha )-sin^2 \alpha cos \alpha }{1-cos \alpha }=\\\\=\frac{(1-cos^2 \alpha )-sin^2 \alpha cos \alpha }{1-cos \alpha }=\frac{sin^2 \alpha -sin^2 \alpha cos \alpha }{1-cos \alpha }=\\\\=\frac{sin^2 \alpha (1-cos \alpha )}{1-cos \alpha }=sin^2 \alpha$