1+Sina=2Cos2(п/4-а/2)

[latex]1+sinalpha=2cos^{2}(frac{pi}{4}-frac{alpha}{2}) \1+sinalpha=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)))))))))))