[tex]\displaystyle\bf\\\frac{Sin(\alpha +\beta )-Sin\beta \cdot Cos\alpha }{Sin(\alpha -\beta )+Sin\beta \cdot Cos\alpha } =\frac{Sin\alpha Cos\beta +Cos\alpha Sin\beta -Sin\beta Cos\alpha }{Sin\alpha Cos\beta -Cos\alpha Sin\beta +Sin\beta Cos\alpha } =\\\\\\=\frac{Sin\alpha Cos\beta }{Sin\alpha Cos\beta } =1\\\\\\Otvet \ : \ 1[/tex]