от Nathi123 » 28 Дек 2016, 19:56
B= [tex](sin\frac{\alpha}{2}+cos\frac{\alpha}{2})^{2}(1+sin\alpha )^{-1} = \frac{sin^{2}\frac{\alpha}{2}+2sin\frac{\alpha}{2}cos\frac{\alpha}{2}+cos^{2}\frac{\alpha}{2}}{1+sin\alpha}=\frac{1+2sin\frac{\alpha}{2}cos\frac{\alpha}{2}}{1+sin\alpha}=\frac{1+sin\alpha}{1+sin\alpha} = 1.[/tex]