1+Sina=2Cos2(п/4-а/2)

[latex]1+sin\alpha=2cos^{2}(\frac{\pi}{4}-\frac{\alpha}{2}) \\1+sin\alpha=1+cos(\frac{\pi}{2}-\alpha)=sin^{2}(\frac{\pi}{4}-\frac{\alpha}{2})+cos^{2}(\frac{\pi}{4}-\frac{\alpha}{2})+\\+cos^{2}(\frac{\pi}{4}-\frac{\alpha}{2})-sin^{2}(\frac{\pi}{4}-\frac{\alpha}{2})=2cos^{2}(\frac{\pi}{4}-\frac{\alpha}{2}) [/latex] Ч.Т.Д)))))))))))